EP3002405A2

EP3002405A2 - Silencing arrangement

Info

Publication number: EP3002405A2
Application number: EP14187298.6A
Authority: EP
Inventors: Lennart KARLÉN; Hans Castwall
Original assignee: Casamja AB
Current assignee: Casamja AB
Priority date: 2014-09-15
Filing date: 2014-10-01
Publication date: 2016-04-06
Also published as: SE541181C2; EP3002405A3; SE1451077A1

Abstract

According to the invention, there is provided a silencing arrangement for installation (11) in a through opening in a window frame or in another opening through a separating surface. The arrangement comprises a plurality of air channels (14) which extend along the entire or substantially the entire depth of the silencing arrangement, which air channels are separated by sound absorbing elements (13) which are fixated relative each other. A first end of each of at least two of the sound absorbing elements has another width than the respective other end. The at least two sound absorbing elements of the sound absorbing elements are alternately arranged such that every other of these at least two sound absorbing elements taper in the depth direction of the silencing arrangement, and the remaining of these at least two sound absorbing elements expand in the depth direction, thereby making at least one of the air channels disposed at an angle relative the depth direction of the silencing arrangement.

Description

Field of the invention

The invention relates to the field of silencing arrangements for installation in a through opening in a window frame, wall or the like.

Background

In order to supply fresh air to a room in a residence or the like, valves which may be installed on, in or at a window frame may be used. Such valves usually have an elongated shape and control the flow through one or more through openings in the window frame or in an adjacent separating surface, which through holes may be in the form of a slit or a plurality of holes.
In order to reduce noise from such a fresh air supply arrangement it is known to install silencers in the above described one or more through openings. Several manufacturers today supply silencers intended to be mounted in a slit-shaped opening.
SE 522703 discloses such a silencing arrangement, which comprises a sound absorbing material which has a number of holes extending through the material, which holes are surrounded by material of a certain thickness. One disadvantage with this solution is that it is not always suitable in applications which require a very low installation height.
An alternative solution is formed with two parallel plate shaped elements, for example metal sheets, between which a plurality of spacing elements are arranged in parallel and at distance from each other. The distance between the spacing elements form channels, i.e. a plurality of parallel channels are separated by the spacing elements. A disadvantage with this solution is that it may provide insufficient sound attenuation in noisy environments, i.e. the noise reduction capacity is limited.

Summary

An object of the present invention is to provide a silencing arrangement with improved sound attenuation, which preferably also has a low flow resistance, and which preferably also is possible to manufacture with a low installation height.
These and other objects are achieved by the present invention by means of a silencing arrangement according to the independent claim. Preferred embodiments are defined in the dependent claims.
According to the invention, there is provided a silencing arrangement for installation in a through opening in a window frame or in another opening through a separating surface. The arrangement comprises a plurality of air channels which extend along the entire or substantially the entire depth of the silencing arrangement, which air channels are separated by sound absorbing elements which are fixated relative each other. A first end of each of at least two of the sound absorbing elements has another width than the respective other end. The at least two sound absorbing elements of the sound absorbing elements are alternately arranged such that every other of these at least two sound absorbing elements taper in the depth direction of the silencing arrangement, and the remaining of these at least two sound absorbing elements expand in the depth direction, thereby making at least one of the air channels disposed at an angle relative the depth direction of the silencing arrangement.
Alternatively, the latter may be described in that a first subset and a second subset of the sound absorbing elements are alternately arranged (i.e. arranged after or next to each other where every other element belong to the first subset and the other elements belong to the second subset), where the first subset of elements is arranged such that they taper in the depth direction of the silencer, and the second subset of elements are arranged such that they expand in the depth direction, thereby making the air channels disposed at an angle relative the depth direction of the silencing arrangement.
The invention is based on the insight that an improved sound attenuation may be provided by channels which are disposed at an angle relative the depth direction of the silencer or relative the incoming flow direction. The invention is further based on the insight that the difference in impedance which is present between two adjacent sound absorbing elements of different widths is advantageous with respect to sound attenuation in a varied and wide frequency range.
It is understood that the depth direction of the silencer or silencing arrangement refers to a direction which is perpendicular to the window frame or the separating surface through which the silencing arrangement is intended to be installed, or in other words a direction which is perpendicular to the front and back sides of the silencing arrangement, i.e. its inlet and outlet sides, or in other words a direction which is parallel with the main flow direction in and/or out from the silencing arrangement.
According to an embodiment of the invention, said first and/or said second ends have rounded edges with a radius of at least 2 mm. This is advantageous since it provides a lower flow resistance through the silencer.
According to another embodiment of the invention, said at least one of the air channels which is disposed at an angle has a cross sectional area which increases in the depth direction of the silencing arrangement or in the flow direction through the channel. This is advantageous since it provides a lower flow resistance through the silencer.
According to yet another embodiment of the invention, the side surfaces of said at least two sound absorbing elements which limit or define said at least one of said air channels are plane. According to yet another embodiment, at least one of the side surfaces of said at least two sound absorbing elements which limits or defines the at least one of said air channels is wholly or partially concave or convex. In other words, the at least one of the air channels may have a non-constant cross section or width. In embodiments where at least one of the side surfaces of the at least two of the sound absorbing elements which limits or defines the at least one of the air channels is wholly or partially concave, the cross sectional area or width may be maximum at a position between the inlet and outlet of the silencing arrangement. This may also be described in that the at least one of the air channels is provided with a cavity between the inlet and outlet. This embodiment is advantageous because it may provide increased sound attenuation in a certain frequency range, which frequency range depends on the chosen geometry of the side surface or side surfaces.
According to yet another embodiment of the invention, at least one of the side surfaces of said at least two sound absorbing elements which limits or defines said at least one of said air channels is wholly or partially concave, and at least one second opposite side surface of said at least two sound absorbing elements is wholly or partially convex, such that said at least one of said air channels is bent or curved in its flow direction, or in other words has a bent or curved flow direction. In other words, at least two side surfaces which are directed towards each other and limit said at least one of said air channels are formed such that one of the side surfaces is wholly or partially concave and the other of the side surfaces is wholly or partially convex. The shape or curvature of the side surface or surfaces which is wholly or partially concave may correspond to the shape or curvature of the side surface or surfaces which is wholly or partially convex, thereby making the width of the air channel or channels substantially constant. This embodiment is advantageous because it may provide further improved sound attenuation.
According to yet another embodiment of the invention, at least one of the sound absorbing elements has another density than at least one other of said sound absorbing elements. According to yet another embodiment of the invention, the sound absorbing elements which taper in the depth direction of the silencing arrangement have another density than the sound absorbing elements which expand in said depth direction. In other words, adjacent sound absorbing elements have different densities. Having sound absorbing elements of different densities is advantageous because it provides a further possibility to tune the sound attenuation to the specific type of noise (road traffic, rail traffic, air traffic etc.) which is present in the environment in which the silencing arrangement is to be installed. In other words, it is thus possible, besides adjusting the geometry of the sound absorbing elements (and consequently channel width, channel angle, channel expansion among others), to also adjust the density of each of the sound absorbing elements to optimize the sound attenuation. It may for example be advantageous at low frequencies to have sound absorbing elements of relatively low density, while it may be advantageous at high frequencies to have a more dense material with higher density.
According to yet another embodiment of the invention, at least one of the sound absorbing elements has a non-constant or varying density, wherein the density at a first end of the at least one of the sound absorbing elements differs from the density at its other end. This is advantageous since it provides further degrees of freedom to tune the sound attenuation to the specific type of noise (road traffic, rail traffic, air traffic etc.) which is present in the environment in which the silencing arrangement is to be installed. In one embodiment, the density is higher at one end than at the other, wider, end and decreases gradually, for example linearly there between. In such a manner, the wider end with low density provides good attenuation at low frequencies and the narrower end with high density provides good attenuation at high frequencies. In another embodiment, the density varies in the lateral direction. The sound absorbing elements may for example be configured such that one half has one density and the other half has another density, e.g. they are divided with respect to density in the depth direction.
According to yet another embodiment of the invention, the silencing arrangement comprises first and second plate shaped elements arranged in parallel and at a distance from each other, wherein the sound absorbing elements are fixed between said plate shaped elements. The sound absorbing elements may also be plate shaped with a substantially rectangular cross section. This provides well defined channels having a rectangular cross section which is limited upwards and downwards by the plate shaped elements and in the lateral direction by two sound absorbing elements. The sound absorbing elements may in another embodiment be described as substantially triangular. In other words, the sound absorbing elements has a substantially triangular cross section seen from above.
According to yet another embodiment of the invention, the silencing arrangement has a height in the interval 5-500 mm, and preferably a height of less than 50 mm, or less than 15 mm.

Brief description of the drawings

These and other aspects of the present invention will now be described in more detail with reference to the appended drawings, which show presently preferred embodiments of the invention, wherein:

fig. 1 shows a known silencing arrangement,
fig. 2 shows a silencing arrangement according to a first embodiment of the invention,
fig. 3 shows a silencing arrangement according to a second embodiment of the invention,
fig. 4 shows a silencing arrangement according to a third embodiment of the invention, and
fig. 5 shows a silencing arrangement according to a fourth embodiment of the invention.

Detailed description

Figure 1 shows a perspective view of part of a known silencing arrangement 1 having a first plate shaped element 2 on which spacing elements 3a-e are arranged in parallel and at distance from each other. Parallel channels 4a-d are formed between the spacing elements 3a-e, through which channels the incoming flow F is distributed. The silencing arrangement also comprises a second plate shaped element which is not shown in the figure. The other plate shaped element is of the same type as the first plate shaped element and is arranged in parallel with the latter on the spacing elements 3a-e, thereby constituting an upper limitation of the channels 4a-d. The channels are thus defined by the two plate shaped elements and the spacing elements. The spacing elements 3a-e are made from a sound absorbing material in order to provide the desired sound attenuating effect. The plate shaped elements are formed in plastic, metal, cardboard or the like.
Figure 2 shows a plan view of part of a silencing arrangement 11 according to a first embodiment of the invention. Sound absorbing elements 13a-e are arranged at distance from each other on a first plate shaped element 12. Channels 14a-d are formed between the sound absorbing elements 13a-e. The sound absorbing elements have a rectangular cross section as seen in the depth direction Y of the silencing arrangement, such that the channels also have a rectangular cross section.
The silencing arrangement also comprises a second plate shaped element which is not shown in the figure. The second plate shaped element is of the same type as the first plate shaped element and is arranged in parallel with the latter on the sound absorbing elements 13a-e, thereby constituting an upper limitation of the channels 14a-d. A first end 13a1-e1 of each of the sound absorbing elements has a smaller width than the second end 13a2-e2. Consequently, the sound absorbing elements have substantially triangular cross sections as seen in a direction perpendicular to the first plate shaped element 12. The sound absorbing elements are alternately arranged such that every other element 13a- 13c, 13e taper in the depth direction Y, and such that the other elements 13b, 13d expand in the depth direction. Consequently, the channels 14a-d are disposed at angles relative the depth direction Y. In this embodiment, the elements 13a, 13c, 13e taper with the same angle as the elements 13b, 13d expand, such that the channels 14a-d have constant width. The silencing arrangement has an elongated cross section, i.e. has a substantially greater width than height. The sound absorbing elements first and second ends have rounded edges as seen in the depth direction.
Figure 3 shows a plan view of part of a silencing arrangement 21 according to a second embodiment of the invention. Sound absorbing elements 23a-e are arranged at distance from each other on a first plate shaped element 22. Channels 24a-d are formed between the sound absorbing elements 23a-e. The silencing arrangement also comprises a second plate shaped element which is not shown in the figure. The second plate shaped element is of the same type as the first plate shaped element and is arranged in parallel with the latter with the sound absorbing elements there between. This second embodiment differs from the first embodiment in that the channels 24a-d have a width or cross sectional area which increases in the depth direction Y of the silencing arrangement. As is evident from fig. 3, the channels have a width b1 at the inlet and a width b2 at the outlet, where b2>b1. In the present case, this increase in width or cross sectional area is due to that the elements 23a, 23c, 23e taper faster, i.e. with a greater angle, than what the elements 23b, 23d expand. In other words, the ratio between the width at the first end and the width at the second end of elements 23a, 23c, 23e is greater than that of elements 23b, 23d.
Figure 4 shows a plan view of part of a silencing arrangement 31 according to a third embodiment of the invention. Sound absorbing elements 33a-e are arranged at distance from each other on a first plate shaped element 32. Channels 34a-d are formed between the sound absorbing elements 33a-e. The silencing arrangement also comprises a second plate shaped element which is not shown in the figure. The second plate shaped element is of the same type as the first plate shaped element and is arranged in parallel with the latter with the sound absorbing elements there between. This third embodiment differs from the first embodiment in that the channels 34a-d have a non-constant width or cross sectional area, where the width or cross sectional area is at its maximum between the inlet and the outlet of the silencing arrangement. In the figure, the maximum width is represented by b3 which is greater than widths b1, b2 at the inlet and the outlet, respectively. This can also be described in that the channels 34a-d are provided with a cavity between the inlet and the outlet. This is due to that the sound absorbing elements 33b, 33d which expand in the depth direction have side surfaces 33b3-b4, 33d3-d4 which are partially concave. As is evident from the figure, these side surfaces limit the channels 34a-d from one direction. In other embodiments, one or a plurality of the sound absorbing elements 33a, 33c, 33e which taper in the depth direction may have one or both side surfaces which are wholly or partially concave. In yet other embodiments, one, a plurality or all of the sound absorbing elements may have side surfaces which are wholly or partially concave or convex.
Figure 5 shows a plan view of part of a silencing arrangement 41 according to a fourth embodiment of the invention. Sound absorbing elements 43a-e are arranged at distance from each other on a first plate shaped element 42. Channels 44a-d are formed between the sound absorbing elements 43a-e. The silencing arrangement also comprises a second plate shaped element which is not shown in the figure. The second plate shaped element is of the same type as the first plate shaped element and is arranged in parallel with the latter with the sound absorbing elements there between. This fourth embodiment differs from the third embodiment in that the channels are bent or curved and have substantially constant cross sectional area and width. This is due to that the sound absorbing elements 43b, 43d which expand in the depth direction have side surfaces 43b3-b4, 43d3-d4 which are partially concave, and that the sound absorbing elements 43a, 43c, 43e which taper in the depth direction have side surfaces 43a4, 43c3-c4, 43e3 which are partially convex with substantially the same curvature as the partially concave surfaces 33b3-b4, 43d3-d4. In yet other embodiments, one, a plurality or all of the sound absorbing elements may have one or both side surfaces which are wholly or partially concave or convex.
In the first, second, third and fourth embodiments described above, all sound absorbing elements have the same and constant density. Other embodiments correspond to the first, second, third and fourth embodiments, but with the difference that the sound absorbing elements 13a, 13c, 13e, 23a, 23c, 23e, 33a, 33c, 33e which taper in the depth direction of the silencing arrangement have another density than the sound absorbing elements 13b, 13d, 23b, 23d, 33b, 33d which expand in the depth direction, i.e. adjacent sound absorbing elements have different densities. Yet other embodiments correspond to either of the first, second and third embodiments, but with the difference that each of the sound absorbing elements has a varying density, where the density at a first end differs from the density at its second end. The sound absorbing elements may also be formed such that they are divided in their length Y-direction where one half has one density and the other another density.
The description above and the appended drawings are to be considered as nonlimiting examples of the invention. The person skilled in the art realizes that several changes and modifications may be made within the scope of the invention. For example, the silencing arrangement may comprise both straight and angled channels, and the sound absorbing elements in one and the same silencing arrangement may have mutually different shapes and densities. Furthermore, the cross sections of the channels do not need to be rectangular, but may have any shape which is defined by how the edges of the sound absorbing elements are formed. Even though the figures show horizontally aligned silencing arrangements, it is realized that they may equally well be arranged vertically or with any other orientation. The scope of protection is determined by the appended patent claims.

Claims

Silencing arrangement for installation in a through opening in a window frame or in another opening through a separating surface, which arrangement comprises: a plurality of air channels (14a-d; 24a-d; 34a-d; 44a-d) which extend along the entire or substantially the entire depth of the silencing arrangement, wherein said air channels are separated by sound absorbing elements (13a-e; 23a-e; 33a-e; 43a-e) which are fixated relative each other, characterized in that a first end (13a1-e1) of each of at least two sound absorbing elements has another width than the respective other end (13a2-e2), and in that said at least two sound absorbing elements are alternately arranged such that every other of the sound absorbing elements taper in the depth direction (Y) of the silencing arrangement, and the remaining sound absorbing elements expand in the depth direction, thereby making at least one of said air channels disposed at an angle relative the depth direction of the silencing arrangement.
Silencing arrangement according to claim 1, wherein said first and other ends have rounded edges with a radius of at least 2 mm.
Silencing arrangement according to claim 1 or 2, wherein said at least one of said air channels which is disposed at an angle has a cross sectional area which increases in the depth direction of the silencing arrangement.
Silencing arrangement according to any one of the preceding claims, wherein the side surfaces of said at least two sound absorbing elements which limit said at least one of said air channels are plane.
Silencing arrangement according to any one of claims 1-3, wherein at least one of the side surfaces of said at least two sound absorbing elements which limits said at least one of said air channels is wholly or partially concave or convex.
Silencing arrangement according to any one of claims 1-3, wherein at least one of the side surfaces (33b3-b4, 33d3-d4) of said at least two sound absorbing elements which limits said at least one of said air channels is wholly or partially concave, and wherein the cross sectional area or width of said at least one of said air channels is maximum at a position between the inlet and outlet of said silencing arrangement.
Silencing arrangement according to any one of claims 1-3, wherein at least one of the side surfaces (43b3-b4, 43d3-d4) of said at least two sound absorbing elements which limits said at least one of said air channels is wholly or partially concave and at least one opposite side surface (43a4, 43c3-c4, 43e3) of said at least two sound absorbing elements is wholly or partially convex such that said at least one of said air channels is bent or curved in its flow direction.
Silencing arrangement according to any one of the preceding claims, wherein at least one of said sound absorbing elements has another density than at least one other of said sound absorbing elements.
Silencing arrangement according to any one of the preceding claims, wherein the sound absorbing elements which taper in the depth direction of the silencing arrangement has another density than the sound absorbing elements which expand in said depth direction.
Silencing arrangement according to any one of the preceding claims, wherein at least one of said sound absorbing elements has a non-constant density, wherein the density at a first end of said element differs from the density at its other end.
Silencing arrangement according to any one of the preceding claims, further comprising first and second plate shaped elements arranged in parallel and at a distance from each other, wherein said sound absorbing elements are fixed between said plate shaped elements.
Silencing arrangement according to any one of the preceding claims, wherein said at least two sound absorbing elements are substantially triangular.
Silencing arrangement according to any one of the preceding claims having a height in the interval 5-500 mm, and preferably less than 50 mm.
Silencing arrangement according to any one of the preceding claims having a width in the interval 10-1000 mm.
Silencing arrangement according to any one of the preceding claims having a depth in the interval 10-500 mm.