Device for diffracting sound and combination of a noise barrier and the device

Abstract

The invention relates to a device (4) for diffracting sound originating from vehicles traveling along a path, such as a motorway (3) or railroad, which device (4) comprises: - a body having a main surface (10) with a first main direction to be arranged parallel to the path; - a number of resonators (8, 9) arranged in the body, wherein each resonator (8, 9) has a channel with an open first end (11) debouching in the main surface (10) and a closed second end (12), wherein the number of resonators (8, 9) are arranged one behind the other in a direction perpendicular to the first main direction wherein at least one of the number of resonators (8, 9) has a sectional channel with at least a first channel section and a second channel section extending in a different direction than the first channel.

Description

[0001] The invention relates to a device for diffracting sound originating from vehicles traveling along a path, such as a motorway or railroad, which device comprises: a body having a main surface with a first main direction to be arranged parallel to the path; a number of resonators arranged in the body, wherein each resonator has a channel with an open first end debouching in the main surface and a closed second end, wherein the number of resonators are arranged one behind the other in a direction perpendicular to the first main direction.

[0002] Such a device is for example known from EP 2491180 and is arranged along the side of a motorway or railroad.

[0003] The resonators in the body of the device resonate to a particular frequency out of the sound originating from vehicles traveling along a motorway or railroad and push the sound wave traveling over the device in an upward direction. As a result a reduction of the sound impacting the area at ground level next to the motorway or railroad is reduced.

[0004] Another option to reduce sound of a motorway or railroad is to provide a noise barrier next to the motorway or railroad. The higher the noise barrier is, the more reduction of sound is achieved for the area next to the motorway or railroad. Noise barriers could be as high as 4 to 6 meters in order to achieve the required noise reduction. However, such high noise barriers also obstruct the view.

[0005] It also known to use a hybrid form of a noise barrier of lower height with a device according to the preamble on top of the noise barrier. The combination of this hybrid form also reduces noise, but has less impact on the view.

[0006] With such hybrid form, the noise barrier reduces typically the noise with relative high frequencies, while the resonators reduce the noise with relative low frequencies. As a result, the resonators need to have a longer channel, in order to resonate with the lower frequencies. A disadvantage is that due to the increased length of the channels, the size of the body of the device increases. This is undesired.

[0007] An object of the invention is to reduce the above mentioned disadvantages.

[0008] This object is achieved according to the invention with a device according to the preamble, which is characterized in that at least one of the number of resonators has a sectional channel with at least a first channel section and a second channel section extending in a different direction than the first channel.

[0009] By using a sectional channel in which a second channel section has a different direction than the first channel, the required length for the channel of a resonator can still be obtained. By directing the second channel section in another direction, the height can be reduced. For example, the first channel section can depend vertically from the main surface, while the second channel section can for example extend in a horizontal direction.

[0010] In a preferred embodiment of the device according to the invention the first channel section extends perpendicular away from the main surface, while the second channel section extends back towards the main surface. Preferably, the first channel section and second channel section form a U-shape.

[0011] With this embodiment, the height of the body is reduced to half of the required length of the channel. Although the distance to the next resonator will be doubled with this embodiment, the increase in width is typically no problem, as it will extend in horizontal direction and does not impede the view.

[0012] In another embodiment of the device according to the invention, the closed second end of the sectional channel is part of the main surface. This ensures a minimal height of the body of the device.

[0013] In yet another embodiment of the device according to the invention the walls of the channel of each resonator are acoustically substantially non-absorbing and which are free of acoustically absorbing material and absorbent material is not located in the cavity.

[0014] This ensures that a maximal resonance is obtained in the channel of the resonator and accordingly a maximal diffraction of the noise.

[0015] In still a further embodiment of the device according to the invention the open first end of each channel is elongate and extends parallel to the first main direction.

[0016] As the device according to the invention is used along the side of the path the pattern of resonators in a direction along the path should be the same, such that the noise generated by the vehicle is diffracted at the same way, independent of the position along the path.

[0017] In yet a further preferred embodiment of the device according to the invention the body of the device comprises: a bottom plate; a number of elongate strips of increasing width arranged parallel to each other and arranged perpendicular onto the bottom plate; and at least one profile having a U-shaped cross-section, wherein the first leg of the U-shape is longer than the second leg, and wherein the first leg is arranged with its free end perpendicular onto the bottom plate and wherein the first leg is arranged parallel to the number of elongate strips.

[0018] Using a bottom plate with a number of elongate strips and a U-shaped profile arranged thereon, allows for a cost effective way of providing a device according to the invention. The distance between the strips and U-shaped profile as well as the width of the strips can easily be changed and manufactured specifically for the case where the device is used.

[0019] Preferably, the main surface is formed by the free top edges of the number of elongate strips extending upwardly from the bottom plate and by the base of the U-shape of the at least one profile.

[0020] Furthermore preferred, the resonators have resonance frequencies lying in a range corresponding to sound produced by the vehicles traveling along the path.

[0021] The invention also relates to a combination of a noise barrier and a device according to the invention the device is arranged on top the noise barrier.

[0022] This allows for a hybrid solution between a noise barrier and a diffractor device, having the benefit of the reduced height of the device according to the invention.

[0023] Still a further embodiment of the combination according to the invention comprises a path, such as a motorway or railroad, along which vehicles travel, wherein the noise barrier is arranged parallel to the path and wherein the device extends from the top of the noise barrier away from the path.

[0024] These and other features of the invention will be elucidated in conjunction with the accompanying drawings. Figure 1 shows a perspective view of an embodiment of a combination according to the invention. Figure 2 shows a perspective view of an embodiment of a device according to the invention. Figure 3 shows a cross-section of the device according to figure 2. Figure 4 shows a detail of figure 3. Figure 5 shows a cross-sectional detail of another embodiment of the device according to the invention.

[0025] Figure 1 shows a perspective view of an embodiment 1 of the combination according to the invention. The combination 1 has a noise barrier 2 positioned parallel to a path, in particular a motorway 3. A device 4 according to the invention is arranged at the top of the noise barrier 2. This device 4 extends from the top of the noise barrier 2 away from the path 3. The device 4 is arranged parallel to the main direction D and the longitudinal direction of the motorway 3.

[0026] The noise barrier 2 will block part of the sound generated by the traffic on the motorway, while the device 4 according to the invention will diffract the sound, which travels over the top of the noise barrier 2.

[0027] Figure 2 shows a perspective view of the device 4. The device 4 has a bottom plate 5 (see also figure 3) with a number of parallel strips 6 and U-shaped profiles 7. The height of the strips 6 and U-shaped profiles 7 decreases from h 1 at the front of the device 4 towards h 2 at the back of the device 4.

[0028] As a result a number of resonators 8, 9 are provided in the body of the device 4 (see figure 4). The resonators 8 are formed by two adjacent strips 6 and the bottom plate 5, such that a channel is formed having a length l 1 . The formed channel has an open first end 11 debouching in the main surface 10 of the device 4 and has a closed second end 12 formed by the bottom plate 5.

[0029] The resonator 9 is formed by a strip 6, a U-shaped profile 7 and the bottom plate 5. The U-shaped profile 7 has a first leg 13, a base 14 and a second leg 15. The first leg 13 is longer than the second leg 15, such that the first leg 13 is arranged to the bottom plate 5, while the free end of the second leg 15 leaves an opening with the bottom plate 5. As a result a sectional channel is formed having a combined length of S 1 and S 2 . The sectional channel has an open first end 16 debouching in the main surface 10 and a closed second end formed by the base 14 of the U-shaped profile 7, which base 14 is also part of the main surface 10.

[0030] So, with the invention it is possible to provide a resonator 9 with a channel length S 1 and S 2 approximately double of a conventional resonator 8 with a channel length l 1 .

[0031] The width and length of the channels of the resonators 8, 9, which are arranged one behind the other in a direction perpendicular to the first main direction D are tuned to the specific frequency at which the resonator 8, 9 needs to resonate in order to diffract part of the noise traveling over the device 4.

[0032] Figure 5 shows a cross-sectional detail of another embodiment of the device 20 according to the invention. The device 20 has a bottom plate 21 from which a number of strips 22 extend upwardly. In this figure two L-shaped strips 23 are connected with their respective horizontal leg to a strip 22, such that an L-shaped sectional channel 25, 26 for a resonator is formed.

[0033] Another number of strips 24 is arranged onto the horizontal leg of the L-shaped strips 23 to form vertical channels 27 for resonators between the vertical leg of the L-shaped strips 23 and the strip 22 to which the horizontal leg of the L-shaped strip 23 is arranged.

[0034] Clearly, the L-shaped sectional channels 25, 26 have a length of S 2 + S 2 and S 3 + S 4 respectively, which is substantially longer than the length of the vertical channels 27, 28.

[0035] Each of the channels 25, 26, 27, 28 form resonators of the device 20 with specific resonance frequencies to diffract sound away from the main plane 29.

Claims

1. Device for diffracting sound originating from vehicles traveling along a path, such as a motorway or railroad, which device comprises: - a body having a main surface with a first main direction to be arranged parallel to the path; - a number of resonators arranged in the body, wherein each resonator has a channel with an open first end debouching in the main surface and a closed second end, wherein the number of resonators are arranged one behind the other in a direction perpendicular to the first main direction characterized in that at least one of the number of resonators has a sectional channel with at least a first channel section and a second channel section extending in a different direction than the first channel.

2. Device according to claim 1, wherein the first channel section extends perpendicular away from the main surface, while the second channel section extends back towards the main surface.

3. Device according to claim 2, wherein the first channel section and second channel section form a U-shape.

4. Device according to any of the preceding claims, wherein the closed second end of the sectional channel is part of the main surface.

5. Device according to any of the preceding claims, wherein the walls of the channel of each resonator are acoustically substantially non-absorbing and which are free of acoustically absorbing material and absorbent material is not located in the cavity.

6. Device according to any of the preceding claims, wherein the open first end of each channel is elongate and extending parallel to the first main direction.

7. Device according to any of the preceding claims, wherein the body of the device comprises: - a bottom plate; - a number of elongate strips of increasing width arranged parallel to each other and arranged perpendicular onto the bottom plate; and - at least one profile having a U-shaped cross-section, wherein the first leg of the U-shape is longer than the second leg, and wherein the first leg is arranged with its free end perpendicular onto the bottom plate and wherein the first leg is arranged parallel to the number of elongate strips.

8. Device according to claim 7, wherein the main surface is formed by the free top edges of the number of elongate strips extending upwardly from the bottom plate and by the base of the U-shape of the at least one profile.

9. Device according to any of the preceding claims, wherein said resonators have resonance frequencies lying in a range corresponding to sound produced by the vehicles traveling along the path.

10. Combination of a noise barrier and a device according to any of the preceding claims, wherein the device is arranged on top the noise barrier.

11. Combination according to claim 10, further comprising a path, such as a motorway or railroad, along which vehicles travel, wherein the noise barrier is arranged parallel to the path and wherein the device extends from the top of the noise barrier away from the path.

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