Resonance silencer and ventilation duct provided with same

Abstract

The invention relates to a resonance silencer (1) with at least one wall (3) which defines at least one first channel (21) with a first end (211) and a second end (212), wherein the second end (212) is closed and the first end (211) has a first opening (215), wherein the resonance silencer (1) further comprises at least one second channel (22) with a first end (221) and a second end (222), wherein the second end (222) is closed and the first end (221) has a second opening (225), and wherein the first and second channels (21, 22) are arranged rotationally symmetrically to each other in an axis of symmetry (4) of the resonance silencer (1), and the first and second channels (21, 22) are each designed as a λ / 4 resonator with a resonance frequency of about 100 Hz to about 500 Hz. Furthermore, the invention relates to a ventilation duct equipped with such a resonance silencer.

Description

[0001] The invention relates to a resonance silencer comprising at least one wall defining at least one first channel having a first end and a second end, the second end being closed and the first end having a first opening. The resonance silencer further comprises at least one second channel having a first end and a second end, the second end being closed and the first end having a second opening. Furthermore, the invention relates to a ventilation duct equipped with such a resonance silencer. Such resonance silencers can be used to optimize room acoustics.

[0002] A silencer for an air conditioning or ventilation system is known from US 2022 / 0415298 A1. This silencer is designed to reduce the propagation of sound waves in a building via the ventilation ducts. For this purpose, the silencer comprises a first wall and a second wall that define a duct. However, this known silencer has the disadvantage that the attenuation of low frequencies is inadequate unless the silencer takes up a large amount of space. However, during operation of fans or other conveying equipment, low frequencies in the range of approximately 50 Hz to approximately 400 Hz are generated, which are perceived as disturbing within the building and whose attenuation with known silencers is only possible to a limited extent.

[0003] Based on the prior art, the invention is therefore based on the object of providing a silencer which effectively attenuates even low frequencies so that they are perceived as less disturbing in the building.

[0004] In some embodiments of the invention, the object can be achieved by a resonance silencer. In at least one embodiment, the resonance silencer can have a wall that defines at least one first channel. The first channel can have a first end and an opposite second end. The first channel can be straight. In other embodiments of the invention, the first channel can be straight in sections with kinks or bends arranged in between. Finally, the first channel can be curved at least in sections or even completely.

[0005] In some embodiments, the second end of the first channel may be closed, ie the first channel has at the second end either a completely closed wall or a wall which has only small openings which are not acoustically effective.

[0006] In some embodiments, the first end of the channel may have a first opening. The first opening may be configured to receive an air flow or to allow an air flow to enter the first channel through the first opening. This air flow may be oscillating and thus represent a sound wave.

[0007] In some embodiments, the resonance silencer may further include at least one second channel. The second channel may have a first end and an opposite second end. The second channel may be straight. In other embodiments, the second channel may be straight in sections with kinks or bends arranged in between. Finally, the second channel may be curved at least in sections or even completely.

[0008] In some embodiments, the second end of the second channel may be closed, ie the second channel has either a completely closed wall at the second end or a wall which has only small openings which are not acoustically effective.

[0009] In some embodiments, the first end of the second channel may have a first opening. The first opening may be configured to receive an air flow or to allow an air flow to enter the second channel through the first opening. This air flow may be oscillating and thus represent a sound wave.

[0010] In some embodiments, it is now proposed that the first and second channels be arranged rotationally symmetrically to one another along an axis of symmetry of the resonance silencer. This feature can result in the resonance silencer having greater damping than known resonance silencers with only one channel. Furthermore, the resonance silencer can dampen sound from different directions, provided the first and second openings of the first and second channels point in different directions. This can reduce the installation space required for the resonance silencer, particularly when sound impinges on the resonance silencer from different directions.

[0011] In some embodiments, the first and second channels may have a common wall in at least one longitudinal section. This can reduce the manufacturing effort of the resonance silencer. Furthermore, in some embodiments, the weight of the resonance silencer and / or the required installation space can be reduced.

[0012] In some embodiments, the first and second channels can have twofold symmetry along an axis of symmetry of the resonance silencer. This means that the first and second channels are arranged relative to each other such that the first channel can be conceptually aligned with the second channel by rotating it 180°. The resonance silencer thus has a C2 axis in Schönflies symbolism. This allows the first and second openings to point in opposite directions, allowing sound from opposite directions to be reduced by the resonance silencer.

[0013] In some embodiments, the resonance silencer may have exactly two channels, ie the first and the second channel, but no further channels.

[0014] In some embodiments, the first and second channels may have the same shape and size. Since both channels have the same resonant frequency, sound at that frequency is dampened particularly effectively.

[0015] In some embodiments, the first and second ducts can have a non-zero curvature. The curvature is defined, as usual, as the second derivative of the curve. A non-zero curvature means that the first and second ducts do not run in a straight line over their entire length. A curved duct can achieve a considerable longitudinal extension, thus effectively damping low frequencies in particular, without reaching a size that makes integration into room or process air conditioning systems difficult or impossible.

[0016] In some embodiments, the first and second channels can be curved at least in sections. In this way, straight sections can be connected by curved sections, allowing the shape of the channel to be adapted to the available installation space.

[0017] In some embodiments, the first and second channels may include at least one bend adjacent to at least one straight section.

[0018] In some embodiments, the first and second ducts may have a square cross-section. In some embodiments, the square cross-section may be rectangular. This allows, for example, production as a continuous strand that only needs to be cut to length before installation in a room or process air conditioning system. Furthermore, integration into rectangular ventilation ducts can be simplified.

[0019] In some embodiments, the resonance silencer can be manufactured in one piece. This can be achieved, for example, by bending a sheet metal strip and / or by extrusion and / or by extrusion.

[0020] In some embodiments, the resonance silencer can be made of a metal, alloy, or polymer. This allows for ease of manufacturing while maintaining low weight and mechanical stability.

[0021] In some embodiments, the wall thickness can be between approximately 0.3 mm and approximately 1.5 mm. In other embodiments, the wall thickness can be between approximately 0.4 mm and approximately 0.8 mm. This allows the resonance silencer to be easily manufactured, lightweight, and highly mechanically stable, particularly in environments where the air flow carries abrasive contaminants.

[0022] In some embodiments, the first and second channels can each have a length of about 20 cm to about 170 cm. In other embodiments, the first and second channels can each have a length of about 30 cm to about 85 cm. In still other embodiments, the first and second channels can each have a length of about 25 cm to about 80 cm. This is the full, acoustically effective length of the channels, even if they are not straight due to bends or kinks. The length of the first and second channels influence the resonance frequency and the damping behavior, so that the resonance silencer can be optimized for a given application.

[0023] In some embodiments, the first and second channels can each be configured as a λ / 4 resonator with a resonant frequency of approximately 100 Hz to approximately 500 Hz. In other embodiments, the first and second channels can each be configured as a λ / 4 resonator with a resonant frequency of approximately 200 Hz to approximately 300 Hz. Such a resonance silencer can, in particular, effectively suppress noise generated by blowers, fans, or other air-conveying devices that propagate through ventilation ducts in the building. This can be a useful addition to a known splitter silencer for higher frequencies, for example, to effectively suppress low-frequency fan noise.

[0024] In some embodiments, a flange and / or a sealing element can be arranged at the upper and / or lower edges of the resonance silencer. This allows the resonance silencer to be easily inserted into a ventilation duct, with the base and cover of the ventilation duct simultaneously forming the upper and lower closures of the resonance silencer, respectively, so that the first and second channels formed in the resonance silencer are closed on all sides except for the first and second openings.

[0025] In some embodiments, the resonance silencer can have a length and / or a width of approximately 100 mm to approximately 220 mm. In other embodiments, the resonance silencer can have a length and / or a width of approximately 125 mm to approximately 200 mm. In these cases, the dimensions of the resonance silencer are compatible with the dimensions of common baffle silencers, so that a baffle silencer can be easily replaced with the resonance silencer proposed here, or the resonance silencer can be easily combined with baffle silencers for higher frequencies.

[0026] In some embodiments, this relates to a ventilation duct with a resonance silencer as described above. The resonance silencer can be arranged inside the ventilation duct. The resonance silencer can thus be integrated into a building without requiring additional installation space.

[0027] In some embodiments, the resonance silencer can be narrower than the ventilation duct and positioned approximately symmetrically within the ventilation duct. This allows room or process air to flow past the resonance silencer on both sides, effectively dampening sound waves in the ventilation duct.

[0028] In some embodiments, a ventilation duct can contain between one and six resonance silencers. In other embodiments, a ventilation duct can contain between two and four resonance silencers. In some embodiments, the resonance silencer(s) can have a sound attenuation of approximately 30 dB to approximately 60 dB in at least one frequency band. In other embodiments, the resonance silencer can have a sound attenuation of approximately 40 dB to approximately 50 dB in at least one frequency band. This allows disturbing ventilation noises in buildings to be dampened to such an extent that they are no longer perceived as disturbing by the building's occupants.

[0029] In some embodiments, the ventilation duct may have a U-rail designed to accommodate at least one resonance silencer. This allows for easy positioning and reliable, sealed installation of the proposed resonance silencer in the ventilation duct. The U-rail can be attached to the floor and / or cover of the ventilation duct by gluing, riveting, screwing, or welding.

[0030] The invention will be explained in more detail below with reference to figures and exemplary embodiments without limiting the general inventive concept. Figure 1 shows a resonance silencer according to a first embodiment in plan view. Figure 2 explains a possible manufacturing method of the resonance silencer according to Figure 1 . Figure 3 shows the resonance silencer according to Figure 1in section. Figure 4 shows a second embodiment of a resonance silencer in section. Figure 5 shows a third embodiment of a resonance silencer in section. Figure 6 shows a fourth embodiment of a resonance silencer in section. Figure 7 shows the installation of a resonance silencer in a ventilation duct according to a first embodiment. Figure 8 shows the installation of a resonance silencer in a ventilation duct according to a second embodiment. Figure 9 shows the transmission attenuation of the resonance silencer according to Figure 1 .

[0031] Based on the Figure 1, 2 and 3 A first embodiment of the proposed resonance silencer is explained in more detail. As can be seen from Figure 1As can be seen, the proposed resonance silencer 1 is approximately cuboid-shaped. The resonance silencer 1 is made from a single layer of material, for example a sheet metal, by bending. The sheet metal can be, for example, an aluminum sheet or a steel sheet. The sheet metal can be provided with a coating, for example an anodized layer, a hot-dip galvanized layer, a paint coating, or a bituminous coating. This can improve corrosion resistance or influence vibration behavior. The sheet metal forms the wall 3 of a first channel 21 and a second channel 22.

[0032] The first channel 21 has a first end 211 and a second end 212. The second end 212 is located inside the cuboid-shaped resonance silencer and is closed. In contrast, the first end 211 has a first opening 215. An air flow, in particular an oscillating air flow or a sound wave, can enter the first channel 21 through this opening 215.

[0033] Furthermore, the resonance silencer 1 has a second channel 22. The second channel 22 also has a first end 221 and a second end 222. The second end 222 of the second channel 22 is also closed. The first end 221 of the second channel 22 has a second opening 225. An air flow, in particular an oscillating air flow or a sound wave, can also enter the second opening 225 into the second channel 22.

[0034] Due to the cuboid shape of the resonance silencer 1, the first and second openings 215 and 225 as well as the first and second channels 21 and 22 have a substantially rectangular cross-section. The width of a channel can be between approximately 10 mm and approximately 50 mm or between approximately 20 mm and approximately 35 mm.

[0035] As from Figure 1 As can be seen, both the first and second channels 21 and 22 have four straight sections connected by right-angled bends. The entire length of the respective channel 21, 22 is thus wound up like a wind instrument to save space.

[0036] In some embodiments, the height of the resonance silencer measured between the upper edge 11 and the lower edge 12 can correspond to the internal height of a ventilation duct, so that the resonance silencer can be easily installed in a ventilation duct by gluing or clamping, with or without intermediate sealing elements. Furthermore, the footprint of the resonance silencer according to the invention can be selected so that it does not require any more installation space than known splitter silencers with mineral wool filling. This allows for easy replacement or compatibility with the known splitter silencers.

[0037] As in particular the cross-section according to Figure 3As shown, the first channel 21 and the second channel 22 have the same shape and size. Both channels are arranged rotationally symmetrically to one another about an axis of symmetry 4 of the resonance silencer 1. This means that the first and second channels are arranged relative to one another in such a way that the first channel can be conceptually aligned with the second channel by rotating it 180°. Likewise, the second channel 22 can be conceptually aligned with the first channel 21 by rotating it 180°. The first and second channels 21 and 22 thus have a common wall 3 in some longitudinal sections.

[0038] The total unwound length of a channel 21 or 22 can range from approximately 20 cm to approximately 170 cm. This allows each of the channels 21 and 22 to function as a λ / 4 resonator with a resonant frequency of approximately 100 Hz to approximately 500 Hz or approximately 200 Hz to approximately 300 Hz.

[0039] If the resonance silencer according to the invention is exposed to sound on both sides, it can reduce sound propagation by approximately 6 dB to approximately 8 dB. A plurality of resonance silencers connected sequentially in series can achieve a correspondingly greater sound reduction.

[0040] Based on the Figure 2 The possible production of a resonance silencer is explained in more detail. As in Figure 2 As can be seen, the resonance silencer 1 according to the first embodiment is manufactured from a single sheet of metal or alloy by multiple bending. The sheet used as a semi-finished product thus forms the wall 3 of the subsequent resonance silencer 1. The sheet can have a thickness of approximately 0.3 mm to approximately 1.5 mm. In some embodiments, the wall thickness can be between approximately 0.4 mm and approximately 0.8 mm.

[0041] For production, a bending tool with a press ram 63 and a die 64 is used. The press ram 63 has an elongated shape and a comparatively low height, so that it can be received on the inside of the channel 21 or 22 being formed. The press ram 63 is connected to the tool holder 61 of a hydraulic press via elongated receiving elements 62 engaging on the end faces. Through the interaction of the die 64 with the press ram 63, approximately right-angled bends can be machined into the wall 3. By bending ten times, the Figure 1 The complex resonance silencers shown are manufactured.

[0042] It should be noted that the Figure 2 The manufacturing process shown is to be understood as an example only. In other embodiments, the Figure 1 or Figure 3The profile of the resonance silencer shown can also be manufactured by extrusion, or injection molding from an aluminum alloy or a polymer, especially a thermoplastic. The resonance silencer can then be manufactured as a continuous profile and cut to the desired height.

[0043] Based on the Figure 4 The cross-section of a second embodiment of the resonance silencer is explained in more detail. Identical components of the invention are provided with the same reference numerals, so the description is limited to the essential differences.

[0044] How Figure 4shows, the second embodiment also contains two channels 21 and 22, which are closed on one side and have a first and second opening 215 and 225 on one side. The channels 21 and 22 according to the second embodiment have a smaller number of bends. This can simplify production. Furthermore, the respective length measured between the first end 211 and the second end 212 can be shorter, resulting in a higher resonance frequency. It goes without saying that the person skilled in the art will adapt the length of the channels and thus the resonance frequency of the resonance silencer to the respective application or the respective noise spectrum to be dampened.

[0045] Based on the Figure 5 A third embodiment of the resonance silencer is explained in more detail. In the cross-section of the third embodiment, identical components are provided with identical reference numerals.

[0046] The resonance silencer according to the third exemplary embodiment also has two channels 21 and 22, each of which has only a single kink or bend. The respective channels thus have the shape of a capital L. In the central area, the first channel 21, on the one hand, and the second channel 22, on the other hand, do not have a common wall section, so that a cavity 25 is created there. The cavity 25 can be provided with a porous sound absorber or can also accommodate fastening elements for the resonance silencer. The axis of symmetry 4, around which the first and second channels 21 and 22 are arranged rotationally symmetrically to one another, is again arranged at the center of the central cavity 25.

[0047] Based on the Figure 6The cross-section of a fourth embodiment of the resonance silencer is explained in more detail. The resonance silencer according to the fourth embodiment does not have a straight longitudinal section. This creates the optical impression of a spiral. The outer contour of the resonance silencer is therefore not cuboid-shaped, as in Figure 1 shown, but elliptical.

[0048] Based on the Figure 7 and 8 The integration of a resonance silencer according to the invention into a ventilation duct 5 is explained in more detail. Figure 7 As shown, the ventilation duct in the illustrated embodiment has an approximately rectangular cross-section. The ventilation duct 5 can be manufactured from sheet steel or plastic in a conventional manner.

[0049] In the illustrated embodiment, three resonance silencers 1a, 1b, and 1c are arranged symmetrically in the ventilation duct, with the first openings 215 facing one side and the opposite second openings 225 facing the other side. In other embodiments, the number of resonance silencers used can also be greater or fewer. For example, between one and six or even between two and four resonance silencers can be used at one location in the ventilation duct. These can have identical or different resonance frequencies.

[0050] When the ventilation duct is in operation in an air-conditioning system or a process air-conditioning system, the air flows past the resonance silencers on the right and left. Along with the air, disruptive noise emissions are transmitted through the ventilation duct, for example, by fans or other conveying devices used to maintain the air flow through the ventilation duct. The disruptive noise emissions can penetrate the first and second ducts of the resonance silencers 1a, 1b, and 1c via openings 215 and 225. Due to the ducts' effect as λ / 4 resonators, the noise emission is attenuated by approximately 30 dB to approximately 60 dB or by approximately 40 dB to approximately 50 dB in a frequency band determined by the length of the duct. At the opening of the ventilation duct, for example in a living or work space, the noise emission can therefore no longer be perceived or can only be perceived in a muffled manner.A larger number of resonance silencers results in a greater attenuation of the disturbing sound emissions.

[0051] How Figure 7 As further shown, the resonance silencers 1 each have a height corresponding to the interior height of the ventilation duct. The upper edge 11 and the lower edge 12 of each resonance silencer 1 can thus form a seal against the floor and the cover of the ventilation duct 5, respectively. This closes the ducts 21 and 22 on all sides except for the openings 215 and 225, respectively, allowing them to function as λ / 4 resonators.

[0052] Based on the Figure 8 A second embodiment of a ventilation duct 5 is explained in more detail. The same components are provided with the same reference numerals, so that the following description is limited to the essential differences. As in Figure 8As can be seen, the ventilation duct 5 contains a U-rail 55 at the bottom. This can be fastened to the material of the ventilation duct 5 by gluing, soldering, welding, or riveting. The U-rail can serve, on the one hand, as a positioning aid into which the resonance silencers 1a, 1b, and 1c can be inserted to ensure essentially symmetrical positioning within the ventilation duct 5. Furthermore, the U-rail can also serve to seal the underside 12 of the resonance silencer. For this purpose, a sealing element made of a polymer or rubber can be inserted into the U-rail.

[0053] Even if this is Figure 8 is not shown, a similar U-rail can be arranged on the cover of the ventilation duct 5.

[0054] Figure 9 explains the transmission loss on the ordinate against the frequency on the abscissa for the first embodiment of a resonance silencer, as shown in the Figure 1and 3 The resonance silencer used as an example has an edge length of 125 mm. The resonance silencer is therefore compatible with standard splitter silencers in terms of dimensions and can therefore be easily used as an exchange or in addition to standard splitter silencers. The length of the two channels 21 and 22 in the illustrated example is 34 cm each. This results in a resonance frequency of the λ / 4 resonator of approximately 250 Hz. Figure 9 As shown, the transmission loss of three resonance silencers installed one after the other in a ventilation duct reaches its maximum value of 35 dB at this resonance frequency. In addition, higher frequencies between approximately 330 Hz and 450 Hz are also effectively attenuated, so that low-frequency noise emissions from fans are efficiently attenuated.

[0055] Of course, the invention is not limited to the illustrated embodiments. The above description is therefore not to be considered restrictive, but rather illustrative. The following claims are to be understood as meaning that a stated feature is present in at least one embodiment of the invention. This does not exclude the presence of further features. Where the claims and the above description define "first" and "second" embodiments, this designation serves to distinguish between two similar embodiments without establishing a priority.

Claims

1. Resonance silencer (1) with at least one wall (3) which delimits at least one first channel (21) with a first end (211) and a second end (212), wherein the second end (212) is closed and the first end (211) has a first opening (215), and the resonance silencer (1) further comprises at least one second channel (22) with a first end (221) and a second end (222), wherein the second end (222) is closed and the first end (221) has a second opening (225), characterized in that the first and second channels (21, 22) are arranged rotationally symmetrically to one another in an axis of symmetry (4) of the resonance silencer (1) and the first and second channels (21, 22) are each designed as a λ / 4 resonator with a resonance frequency of approximately 100 Hz to approximately 500 Hz.

2. Resonance silencer according to claim 1, characterized in thatthe first and second channels (21, 22) have a common wall in at least one longitudinal section.

3. Resonance silencer according to claim 1 or 2, characterized in that the first and second channels (21, 22) have a twofold symmetry in the axis of symmetry (4) of the resonance silencer (1) and / or that the resonance silencer (1) has exactly two channels (21, 22).

4. Resonance silencer according to one of claims 1 to 3, characterized in that the first and second channels (21, 22) have the same shape and size.

5. Resonance silencer according to one of claims 1 to 4, characterized in that the first and the second channel (21, 22) have a non-vanishing curvature or that the first and the second channel (21, 22) are curved at least in sections or that the first and the second channel (21, 22) have at least one bend which borders on at least one straight section.

6. Resonance silencer according to one of claims 1 to 5, characterized in that the first and second channels (21, 22) have a square cross-section.

7. Resonance silencer according to one of claims 1 to 6, characterized in that it is made in one piece and / or that it is made of a metal or an alloy or a polymer.

8. Resonance silencer according to one of claims 1 to 7, characterized in that the wall (3) has a wall thickness of approximately 0.3 mm to approximately 1.5 mm or of approximately 0.4 mm to approximately 0.8 mm.

9. Resonance silencer according to one of claims 1 to 8, characterized in that the first and the second channel (21, 22) each have a length of approximately 20 cm to approximately 170 cm or of approximately 30 cm to approximately 85 cm or 25 cm to approximately 80 cm and / or that the first and the second channel (21, 22) are each designed as a λ / 4 resonator with a resonance frequency of approximately 200 Hz to approximately 300 Hz.

10. Resonance silencer according to one of claims 1 to 9, characterized in that on whose upper edge (11) and / or on whose lower edge (12) a flange and / or a sealing element is arranged.

11. Resonance silencer according to one of claims 1 to 10, characterized in that it has a length and / or a width of about 100 mm to about 220 mm or of about 125 mm to about 200 mm 12. Ventilation duct (5) with at least one resonance silencer (1) according to one of claims 1 to 11.

13. Ventilation duct according to claim 12, characterized in that the resonance silencer (1) has a smaller width than the ventilation duct (5) and is arranged approximately symmetrically in the ventilation duct.

14. Ventilation duct according to one of claims 12 or 13, characterized in that which contains between 1 and 6 or between 2 and 4 resonance silencers (1).

15. Ventilation duct according to one of claims 12 to 14, characterized in thatit has an internal height which corresponds to the height of the resonance silencer(s) (1) and / or that the resonance silencer(s) (1) are glued or clamped into the ventilation duct.

Images