Installation for distributing an air flow including an acoustic attenuation sector.

Abstract

Title of the invention: Installation for distributing an air flow comprising an acoustic attenuation sector. The present invention relates to an installation (2) for distributing an air flow, the distribution installation (2) comprising at least one circulation duct (4) comprising an acoustic attenuation sector (6) which comprises at least a first straight portion (8), a second straight portion (10) and a third intermediate portion (12), the first straight portion (8) comprising a first wall (14) inscribed in a first plane (P1) and a second wall (16) inscribed in a second plane (P2), the first wall (14) being opposite the second wall (16), the second straight portion (10) comprising at least one of its walls which is inscribed in an extension plane (P3) extending in a space delimited between the first plane (P1) and the second plane (P2). (Figure 1)

Description

Title of the invention: Installation for distributing an air flow comprising an acoustic attenuation sector.

[0001] The present invention relates to the field of installations, in particular within buildings, for the circulation of an air flow within an air flow circulation duct. The present invention relates more particularly to the field of the reduction of sound frequencies propagating within such an air flow circulation duct.

[0002] In particular, buildings and means of transporting people and / or goods, such as motor vehicles, airplanes, trains, or even ships, are commonly equipped with ventilation systems within which an installation for distributing an air flow is implemented to ensure, for example, the circulation of an air flow through the building, the ship or the means of transport, with or without thermal treatment of this air flow.

[0003] These installations for distributing an air flow conventionally comprise an air flow circulation duct delimiting a passage in which the air flow circulates and a motor-fan unit intended to force the circulation of the air flow through the duct. During the operation of such installations, sound waves are emitted, in particular by the operation of the motor-fan unit, and propagate in the duct generating noise pollution.

[0004] It is known to implement systems for reducing the amplitude of these sound waves propagating through the air flow circulation duct so as to reduce the intensity of the noise pollution. These systems are, for example, formed of a silencer arranged between the motor-fan unit and the circulation duct or of a coating covering an internal wall of the circulation duct to absorb a range of sound frequencies.

[0005] The solutions implemented to reduce the propagation of sound waves within circulation ducts are particularly effective in medium frequencies. However, in low frequencies and in high frequencies, the reduction of the propagation of these sound waves is less effective. In addition, the implementation of additional systems to ensure the reduction of noise emissions by an air flow distribution installation is expensive and cumbersome.

[0006] The present invention falls within this context and proposes to overcome at least some of the drawbacks of the prior art. The present invention proposes in particular to provide an installation for distributing an air flow in which the propagation of sound emissions, in particular in the low frequencies and the high frequencies are reduced and in which the implementation of additional noise reduction systems is limited to improve production costs and reduce the footprint of these airflow distribution installations.

[0007] Thus, the present invention relates to an installation for distributing an air flow, the distribution installation comprising at least one air flow circulation duct provided with walls delimiting an air flow circulation passage, at least one of said walls comprising a panel formed from a first sheet, a second sheet and an insulator interposed between the first sheet and the second sheet, the circulation duct comprising an acoustic attenuation sector which comprises at least a first straight portion, a second straight portion and a third intermediate portion joining said first straight portion and second straight portion, the first straight portion comprising a first wall lying in a first plane and a second wall lying in a second plane, the first wall being opposite the second wall,the second straight portion comprising at least one of its walls which is part of an extension plane extending in a space delimited between the first plane and the second plane.

[0008] The circulation duct allows the air flow to be moved. For this purpose, the circulation duct comprises a plurality of walls which each participate in delimiting the circulation passage of the air flow. The walls are secured to each other so that the circulation passage is hermetically separated from the environment outside the circulation duct. The walls which constitute the circulation duct are self-supporting in the sense that it is their assembly which forms the structure of the duct, without the addition of a frame, in particular. At least two contiguous walls are connected at their corner by adhesive means, the assembly of four walls forming a section or portion of duct.

[0009] These walls delimit portions of the circulation duct such that each portion is secured to another portion to jointly delimit the circulation passage and form the acoustic attenuation sector. Each portion is formed such that the cross-section of the circulation passage is the same for each portion. More specifically, the acoustic attenuation sector comprises at least the first straight portion, the second straight portion and the third intermediate portion which are hermetically secured to each other. The second straight portion is offset perpendicularly to the main elongation direction of the circulation duct relative to the first straight portion.This offset of the second straight portion relative to the first straight portion is such that a wall of the second straight portion extends in the extension plane which extends between the first plane in which the first wall of the first straight portion is inscribed and the second plane in which the second wall of the first straight portion is inscribed.

[0010] It should be understood that the walls which extend in their respective plane extend predominantly in the plane considered. Also, the direction of principal elongation of the walls extends in the plane considered.

[0011] It is understood that the first wall and the second wall of the first straight portion are opposite in that the first wall faces the second wall. In other words, the first wall and the second wall are not adjacent. This makes it possible to define a space between the first wall and the second wall which corresponds to the circulation passage of the air flow within the circulation duct.

[0012] The offset of the second straight portion relative to the first straight portion can be observed by the distance between the second plane and the extension plane which is non-zero. More precisely, the distance between the extension plane and the second plane is less than the distance between the first plane and the second plane. Advantageously, the distance between the extension plane and the second plane is between 10% and 80% of the distance between the first plane and the second plane, preferably between 30% and 70%, more preferably between 40% and 60%. It should be noted that these distances are measured along the shortest segment joining the planes considered.

[0013] According to a characteristic of the invention, the third intermediate portion is inclined relative to the first straight portion and to the second straight portion. By inclined it is understood that the direction of principal elongation of the third intermediate portion is secant to the direction of principal elongation of the first straight portion and of the second straight portion.

[0014] The inclination of the third intermediate portion makes it possible to generate a deviation of the air flow within the acoustic attenuation sector. Indeed, a portion of the air flow is deflected by coming into contact with a wall of the third intermediate portion which extends at least partly across the direction of flow of the air flow within the first straight portion. This deviation of the air flow generated by the inclination of the third intermediate portion makes it possible to reduce the propagation of sound waves within the circulation duct without the need to add additional elements across the circulation duct or to provide a specific coating on the internal walls of the portions of the circulation duct.

[0015] According to a characteristic of the invention, the insulation is formed from a material formed from an entanglement of mineral fibers. These mineral fibers can be formed from glass fibers or rock fibers.

[0016] According to a characteristic of the invention, the first straight portion extends along a first main elongation direction and the second straight portion extends along a second main elongation direction, the first main elongation direction being parallel to the second main elongation direction.

[0017] According to a characteristic of the invention, a wall of the third intermediate portion forms an angle of between 100 degrees and 160 degrees with an adjacent wall of the first straight portion.

[0018] According to a characteristic of the invention, the circulation duct comprises a fourth intermediate portion and a fifth straight portion, the fourth intermediate portion joining the second straight portion and the fifth straight portion.

[0019] According to a characteristic of the invention, the fourth intermediate portion is inclined relative to the second straight portion and relative to the fifth straight portion.

[0020] According to a characteristic of the invention, the wall of the second straight portion which is inscribed in the extension plane extends in a space delimited between a third plane in which one of the constituent walls of the fifth straight portion is inscribed and a fourth plane in which another of the constituent walls of the fifth straight portion is inscribed, said walls being opposite one another. At least one of the walls of the first straight portion is coplanar with one of the walls of the fifth straight portion. As a result, the distance between the extension plane and the fourth plane is less than the distance between the third plane and the fourth plane. It is understood that the second straight portion is offset perpendicularly with respect to the direction of principal elongation of the first straight portion and with respect to the direction of principal elongation of the fifth straight portion.

[0021] According to a characteristic of the invention, the distribution installation comprises at least one volume which extends in the first straight portion, the second straight portion and the third intermediate portion, said volume being delimited by the first plane and by the extension plane. This volume extends successively through the first straight portion, the third intermediate portion, the second straight portion, the fourth intermediate portion and the fifth straight portion. Thus, this volume extends parallel to the main elongation direction of the circulation conduit.

[0022] According to a characteristic of the invention, the volume extends in at least 5% of a passage section of the air flow of the first straight portion.

[0023] According to a characteristic of the invention, the volume extends in the first portion in between 10% and 80% of the passage section of the air flow of the first straight portion. Preferably, the volume extends in the first portion in between 30% and 70% of the passage section of the air flow of the first straight portion. More preferably, the volume extends in the first portion in between 40% and 60% of the passage section of the air flow of the first straight portion.

[0024] The inventors were able to observe that when the dimensions of the volume are almost zero, the gain in acoustic terms is maximum, however the airflow pressure losses are significant. Conversely, when the dimensions of the volume are very large, the air pressure losses are minimal but the acoustic gain is very low. It follows that in the indicated proportions of at least 5%, an optimal compromise between acoustic gain and pressure losses is found.

[0025] According to a characteristic of the invention, the third intermediate portion and the second straight portion form a first bend, the second straight portion and the fourth intermediate portion form a second bend and the fourth intermediate portion and the fifth straight portion form a third bend, the circulation duct comprising a succession of assemblies formed from the first bend, the second bend and the third bend.

[0026] According to a characteristic of the invention, the distribution installation comprises a motor-fan unit configured to circulate the air flow within the circulation duct.

[0027] According to a characteristic of the invention, the third intermediate portion is arranged less than 5 meters from the motor-fan unit. The closer the acoustic attenuation sector is arranged to the motor-fan unit, the more the sound waves generated by the motor-fan unit are prevented from propagating through the circulation duct. Alternatively, the third intermediate portion is arranged less than 5 meters from the end of the distribution installation opposite the motor-fan unit. The acoustic attenuation sector makes it possible to limit the propagation of sound waves within the circulation duct of the distribution installation; also, depending on the implementation constraints of the distribution installation, the acoustic attenuation sector may be arranged at one end of the circulation duct opposite the motor-fan unit.

[0028] The present invention also relates to the use of an installation for distributing an air flow comprising a duct for circulating the air flow, the duct for circulating the air flow comprising an acoustic attenuation sector configured to limit the propagation of sound waves within the circulation duct, the acoustic attenuation sector comprising a plurality of portions of the circulation duct, two adjacent portions being inclined relative to each other for the purpose of reducing the propagation of sound waves in the circulation duct.

[0029] According to a characteristic of the invention, the installation for distributing an air flow is used in a building, or in a means of transporting people and / or goods.

[0030] The implementation of the invention can be carried out in all structures in which an air flow circulates in a circulation duct with a risk of sound waves propagating within this circulation duct.

[0031] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and examples of embodiment given for informational and non-limiting purposes with reference to the schematic drawings annexed elsewhere, in which:

[0032] [Fig.l] schematically represents a view of a part of the installation for distributing an air flow according to an embodiment of the invention in which a circulation duct delimiting a circulation passage of the air flow and comprising an acoustic attenuation sector formed of a plurality of portions is implemented;

[0033] [Fig.2] schematically represents a view of the circulation duct illustrating a volume delimited between two parallel planes and extending within the different portions of the circulation duct;

[0034] [Fig.3] schematically represents a view of the distribution installation in which a motor-fan unit intended to force the circulation of the air flow within the circulation duct is fluidically connected to a portion of the acoustic attenuation sector;

[0035] [Fig.4] graphically represents the reduction of the noise generated in the circulation duct according to the frequency of the sound waves by the attenuation sector compared to a straight circulation duct;

[0036] [Fig.5] schematically represents another embodiment of the invention in which the acoustic attenuation sector is formed from a succession of assemblies formed from the different portions visible in Figures 1 to 3.

[0037] The features, variants and different embodiments of the invention may be combined with each other, in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the state of the art.

[0038] In the figures, the elements common to several figures retain the same reference.

[0039] In the detailed description which follows, the terms “longitudinal”, “transverse” and “vertical” refer to the orientation of an air flow distribution installation as arbitrarily defined by the trihedron L, V, T. A longitudinal direction corresponds to a direction of main elongation of an air flow circulation duct of the air flow distribution installation, this longitudinal direction being parallel to a longitudinal axis L of the reference L, V, T illustrated in the figures. A transverse direction corresponds to a perpendicular direction, in a plane parallel to a floor of a building in which the distribution installation of an air flow is implemented, this transverse direction being parallel to a transverse axis T of the reference L, V, T and this transverse axis T being perpendicular to the longitudinal axis L. Finally, a vertical direction corresponds to a direction parallel to a vertical axis V of the reference L, V, T, this vertical axis V being perpendicular to the longitudinal axis L and to the transverse axis T.

[0040] Figures 1 to 3 illustrate a part of an installation 2 for distributing an air flow equipping a building. This building may, for example, be a building or a ship. It should be noted that the present invention can also be implemented in means of transport. The distribution installation 2 comprises an air flow circulation duct 4 intended to ensure the circulation of an air flow through the building.

[0041] This circulation duct 4 extends along a main elongation direction parallel to the axis L and comprises a plurality of walls delimiting a circulation passage within which the air flow is able to circulate in the circulation duct 4. At least one of these walls, advantageously all the walls of the circulation duct 4, comprises a panel formed of at least a first sheet, a second sheet and an insulator interposed between the first sheet and the second sheet.

[0042] In the embodiment shown, the first sheet is a metal sheet formed from aluminum or an aluminum alloy and forms the outer wall of the circulation duct 4, the second sheet may also be a metal sheet formed from aluminum or an aluminum alloy and forms the inner wall of the circulation duct 4 intended to be in contact with the air flow. Alternatively, the first sheet and the second sheet may be formed from aluminum or other coating such as Kraft aluminum, a reinforced woven glass fiber fabric, a veil made of acrylic glass or the like. Such a composition of the first sheet and the second sheet makes it possible to ensure the sealing of the circulation duct 4, offers lightness and thermal insulation properties, in particular by means of the insulation interposed between the first sheet and the second sheet, optimal for the circulation duct 4.Such a wall is self-supporting in the sense that it remains in a plane without the addition of a structural frame or support element. It is the insulation placed between the two sheets that gives the wall the mechanical strength that allows it to be self-supporting. In the embodiment shown, the insulation is formed from mineral fibers such as glass fibers or rock fibers.

[0043] It should be noted that in an embodiment of the invention not shown here, the interior of the circulation duct 4 can be treated with a porous material making it possible to participate in limiting the propagation of sound waves in the circulation duct 4 while limiting the air pressure losses.

[0044] According to the invention, the circulation duct 4 comprises an attenuation sector acoustic 6 formed from a plurality of portions. More specifically, the acoustic attenuation sector 6 comprises at least a first straight portion 8, a second straight portion 10 and a third intermediate portion 12 joining the first straight portion 8 and the second straight portion 10. It is understood that the third intermediate portion 12 is secured to the first straight portion 8 and to the second straight portion 10 so that the air flow is able to pass successively through the first straight portion 8, the third intermediate portion 12 and the second straight portion 10.

[0045] The connection between these portions 8, 10, 12 is carried out in a hermetic manner so that the air flow circulating in the circulation duct 4 cannot escape from said circulation duct 4 at the junction zones between the different portions 8, 10, 12.

[0046] Each of the first straight portion 8, second straight portion 10 and third intermediate portion 12 is, like the rest of the circulation duct 4, formed of a plurality of walls secured to each other by one end so as to delimit the circulation passage. This circulation passage has, in the embodiment shown, a constant rectangular section all along the circulation duct 4. Said section is produced perpendicular to two opposite walls of the circulation duct 4. It is understood that each portion 8, 10, 12 has a section whose area is substantially equal.

[0047] Also, the first straight portion 8 of the acoustic attenuation sector 6 comprises a first wall 14 which is inscribed in a first plane P1 and a second wall 16, opposite the first wall 14, which is inscribed in a second plane P2. The first wall 14 and the second wall 16 face each other and participate in delimiting the passage for circulation of the air flow. In the embodiment shown, the first wall 14 and the second wall 16 each comprise a panel conforming to what has been described previously. Thus, the second sheet of the first wall 14 is arranged opposite the second sheet of the second wall 16.

[0048] Furthermore, as shown in Figures 1 to 3, the first plane P1 and the second plane P2 are two parallel planes extending parallel to the axes L and V. More specifically, the first straight portion 8 extends along a first main elongation direction parallel to the axis L.

[0049] The second straight portion 10 of the acoustic attenuation sector 6 extends along a second main elongation direction parallel to the axis L, this second main elongation direction is parallel to the first main elongation direction of the first straight portion 8.

[0050] Furthermore, the second straight portion 10 comprises at least one of its walls which is inscribed in an extension plane P3. This extension plane P3 extends in a space delimited between the first plane PI and the second plane P2. This arrangement of the extension plane P3 between the first plane PI and the second plane P2 is permitted by the third intermediate portion 12 which is inclined relative to the first straight portion 8 and to the second straight portion 10.

[0051] Indeed, the inclination of the third intermediate portion 12 makes it possible to generate, in the embodiment shown, an offset parallel to the axis V of the second straight portion 10 relative to the first straight portion 8. The third intermediate portion 12 extends along a third main elongation direction secant to the first main elongation direction of the first straight portion 8 and to the second main elongation direction of the second straight portion 10. More specifically, the inclination of the third intermediate portion 12 relative to the first straight portion 8 and relative to the second straight portion 10 forms a first angle of inclination α between the first straight portion 8 and the third intermediate portion 12 and a second angle of inclination [3 between the second straight portion 10 and the third intermediate portion 12.

[0052] More precisely, the first angle of inclination and the second angle of inclination considered are the angles formed between the different directions of principal elongation considered of each portion 8, 10, 12.

[0053] Indeed, the first main elongation direction, which in the embodiment shown is parallel to the elongation direction of the first wall 14 and the second wall 16 of the first straight portion 8, and the third main elongation direction, which in the embodiment shown is parallel to the elongation direction of a wall of the third intermediate portion 12, form the first angle of inclination a. The first angle of inclination a is between 100 degrees and 160 degrees.

[0054] Furthermore, the second main elongation direction, which in the embodiment shown is parallel to the elongation direction of a wall of the second straight portion 10 opposite the wall of the second straight portion 10 which is inscribed in the extension plane P3, and said third main elongation direction form the second angle of inclination [3. The second angle of inclination [3 is between 100 degrees and 160 degrees. It should be noted that the angle considered for the first angle of inclination a and for the second angle of inclination [3 is the salient angle.

[0055] In the embodiment shown, the first angle of inclination α and the second angle of inclination [3 are equal. It is understood from the above that at least one wall of the third intermediate portion 12 forms an angle of between 100 degrees and 160 degrees with an adjacent wall of the first straight portion 8. In addition, said wall of the third intermediate portion 12 forms an angle of between 100 degrees and 160 degrees with an adjacent wall of the second straight portion 10.

[0056] It is notable that the values ​​of the first angle of inclination a and the second angle of inclination [3 are particularly important because the latter reflect the modification of the flow of the air flow within the attenuation sector 6. Indeed, the closer the value of the first angle of inclination a and the second angle of inclination [3 is to 90 degrees, the greater the airflow losses. Conversely, the more open the first angle of inclination a and the second angle of inclination [3 is, i.e., close to 180 degrees, the more minimal the airflow losses are.

[0057] As visible in [Fig. 3], the distribution installation 2 comprises a motor-fan unit 18 configured to circulate an air flow 20 within the circulation duct 4. The motor-fan unit 18 is fluidically connected to the first straight portion 8 so that the air flow 20 whose circulation is forced through the circulation duct 4 circulates firstly in the first straight portion 8.

[0058] As visible in [Fig. 3], the acoustic attenuation sector 6 makes it possible to generate a deviation of a portion of the air flow 20. Indeed, the air flow 20 circulates in a laminar manner along a laminar flow direction, here parallel to the axis L, throughout the first straight portion 8 then upon reaching the third intermediate portion 12 the air flow 20 is deflected by a wall of the third intermediate portion 12. This deviation is achieved by the inclination of the third intermediate portion 12, the direction of elongation of its walls of which is secant to the laminar flow direction of the air flow 20 in the first straight portion 8.

[0059] The inventors were able to observe that this deviation of the air flow 20 generated by the inclination of the third intermediate portion 12 makes it possible to limit the propagation of sound waves, here generated by the operation of the motor-fan unit 18, through the circulation duct 4.

[0060] This limitation of the propagation of sound waves is particularly visible in [Fig. 4]. [Fig. 4] represents in solid lines a first curve C1 highlighting the reduction of sound in decibels (dB) at different sound frequencies expressed in Hertz (Hz) induced by the acoustic attenuation sector 6, and more precisely the deviation of the air flow 20 generated by the inclination of the third intermediate portion 12. [Fig. 4] represents in dotted lines and for comparison purposes a second curve C2 highlighting the reduction of sound at different sound frequencies of a circulation duct 4 not comprising an acoustic attenuation sector 6 in accordance with the present invention, and more precisely a straight duct.

[0061] It is remarkable in [Fig.4], that the attenuation sector, and more specifically the deviation of the air flow 20 generated by the inclination of the third intermediate portion 12, allows in the low frequencies, in particular between 63 Hz and 630 Hz, and in the high frequencies, in particular between 1600 Hz and 10000 Hz to reduce the sound emission through the circulation duct 4 by 6 dB compared to a duct extending along a single direction of elongation, i.e. a straight duct.

[0062] Therefore, it is understood that a compromise must be implemented within the acoustic attenuation sector 6 so as to limit the propagation of a sound wave within the acoustic attenuation sector 6 and limit the air pressure losses.

[0063] Furthermore, it is remarkable in [Fig. 2] that the inclination of the third intermediate portion 12 is such that the distance between the second plane P2 and the extension plane P3 is less than the distance between the first plane PI and the second plane P2. More specifically, this distance between the extension plane P3 and the second plane P2 is less than at least 80% of the distance between the first plane PI and the second plane P2, preferably less than at least 70% of the distance between the first plane PI and the second plane P2, more preferably less than at least 60% of the distance between the first plane PI and the second plane P2. It should be noted that these distances are measured perpendicular to the first plane PI, the second plane P2 and the extension plane P3.

[0064] This distance between the extension plane P3 and the second plane P2, less than the distance between the first plane PI and the second plane P2, makes it possible to form within the circulation duct 4 a volume 22, visible in particular in [Fig. 2], delimited by the first plane P2 and by the extension plane P3. This volume 22 results from a compromise found, in the embodiment shown, between limiting the propagation of sound waves within the acoustic attenuation sector 6 and limiting the air pressure losses.

[0065] More specifically, the inventors were able to demonstrate that when the deflection of the acoustic attenuation sector 6 induced by the inclination of the third intermediate portion 12 causes the volume 22 to extend into at least 5% of the section of the first straight portion 8, the compromise between the air pressure losses previously mentioned and the limitation of the propagation of sound waves are optimal.

[0066] Furthermore, in the embodiment shown in Figures 1 to 3, the circulation duct 4 comprises a fourth intermediate portion 24 and a fifth straight portion 26, the fourth intermediate portion 24 joining the second straight portion 10 and the fifth straight portion 26.

[0067] The assembly of the different portions 8, 10, 12, 24, 26 of the circulation duct 4 is such that the air flow 20 whose circulation in the circulation duct 4 is forced by the motor-fan unit 18 circulates successively in the first straight portion 8 then in the third intermediate portion 12 then in the second straight portion 10 then in the fourth intermediate portion 24 then in the fifth straight portion 26. It should be noted that what has been described previously in connection with the assembly of the different portions 8, 10, 12 between them, the walls of the different portions 8, 10, 12 and the section of these portions 8, 10, 12 applies mutatis mutandis to the fourth intermediate portion 24 and to the fifth straight portion 26.

[0068] The fourth intermediate portion 24 is, like the third intermediate portion 12 with respect to the first straight portion 8 and the second straight portion 10, inclined with respect to the second straight portion 10 and the fifth straight portion 26. The inclination of the fourth intermediate portion 24 makes it possible to deflect a portion of the air flow 20 in accordance with what has been described in connection with the inclination of the third intermediate portion 12. This additional deflection of the air flow 20 makes it possible to additionally limit the reduction in the propagation of sound waves within the circulation duct 4. It is understood that by increasing the deviations of the air flow, the reduction in sound emissions within the circulation duct 4 is increased.

[0069] In addition, the fifth straight portion 26 extends along the first main elongation direction. Also, the fifth straight portion 26 comprises a wall which is inscribed in a third plane P4 and another wall, opposite said wall which is inscribed in the third plane P4, which is inscribed in a fourth plane P5. It should be noted that in the embodiment shown, the third plane P4 is merged with the first plane P1 and the fourth plane P5 is merged with the second plane P2. Thus, the extension plane P3 extends in a space delimited between the third plane P4 and the fourth plane P5.

[0070] As visible in [Fig.2], it results from this alignment of the walls of the first straight portion 8 with the walls of the fifth straight portion 26 that the volume 22 extends all along the first straight portion 8, the third intermediate portion 12, the second straight portion 10, the fourth intermediate portion 24 and the fifth straight portion 26. Thus, the pressure losses within the acoustic attenuation sector 6 are thus limited while promoting the reduction of the propagation of sound waves.

[0071] It is remarkable in [Fig.l] that the wall of the second straight portion 10 which is inscribed in the extension plane P3 extends between a wall of the third intermediate portion 12 and a wall of the fourth intermediate portion 24 over a distance DI which is less than 50%, preferably less than 45%, more preferably less than 40%, of the length measured parallel to the main elongation direction of the circulation duct 4 of the wall opposite the wall of the second straight portion 10 which is inscribed in the extension plane P3. In the embodiment shown, this distance D1 is between 5 cm and 20 cm, preferably initially between 10 cm and 15 cm. It should be noted that the smaller the distance DI along which the wall of the second straight portion 10 which is inscribed in the extension plane P3 extends, the greater the deviation of the air flow 20 at the level of the acoustic attenuation sector 6 will be, which helps to reduce the propagation of sound waves within the acoustic attenuation sector 6.

[0072] [Fig. 5] illustrates an alternative embodiment of the invention. In this alternative embodiment of the invention, the third intermediate portion 12 and the second straight portion 10 form a first bend 30, the second straight portion 10 and the fourth intermediate portion 24 form a second bend 32 and the fourth intermediate portion 24 and the fifth straight portion 26 form a third bend 34.

[0073] The first elbow 30, the second elbow 32 and the third elbow 34 form an assembly. In this variant embodiment of the invention, the circulation duct 4 comprises a succession of assemblies formed by the first elbow 30, the second elbow 32 and the third elbow 34. The succession of assemblies makes it possible to maximize the reduction of the propagation of sound waves within the circulation duct 4. It is understood that the more the acoustic attenuation sector 6 comprises a large number of assemblies, the greater the reduction in noise generated by the distribution installation 2.

[0074] The present invention as just described achieves the aim it set itself by proposing an installation for distributing an air flow in which the propagation of sound waves within a circulation duct is reduced by means of an acoustic attenuation sector formed of several portions, at least one of which is inclined relative to the others.

[0075] The present invention cannot, however, be limited to the means and configurations described and illustrated here and it also extends to any equivalent means and configuration as well as to any technically effective combination of such means.

Claims

Claims

1. Installation for distributing (2) an air flow (20), the distribution installation (2) comprising at least one circulation duct (4) for the air flow (20) provided with walls delimiting a circulation passage for the air flow (20), at least one of said walls comprising a panel formed from a first sheet, a second sheet and an insulator interposed between the first sheet and the second sheet, the circulation duct (4) comprising an acoustic attenuation sector (6) which comprises at least a first straight portion (8), a second straight portion (10) and a third intermediate portion (12) joining said first straight portion (8) and second straight portion (10), the first straight portion (8) comprising a first wall (14) inscribed in a first plane (PI) and a second wall (16) inscribed in a second plane (P2), the first wall (14) being opposite the second wall (16),the second straight portion (10) comprising at least one of its walls which is inscribed in an extension plane (P3) extending in a space delimited between the first plane (PI) and the second plane (P2).,

2. Distribution installation (2) according to claim 1, in which the third intermediate portion (12) is inclined relative to the first straight portion (8) and to the second straight portion (10).

3. Distribution installation (2) according to any one of claims 1 and 2, in which the first straight portion (8) extends along a first main elongation direction and the second straight portion (10) extends along a second main elongation direction, the first main elongation direction being parallel to the second main elongation direction.

4. Distribution installation (2) according to any one of claims 1 to 3, in which a wall of the third intermediate portion (12) forms an angle of between 100 degrees and 160 degrees with an adjacent wall of the first straight portion (8).

5. Distribution installation (2) according to any one of claims 1 to 4, in which the circulation conduit (4) comprises a fourth intermediate portion (24) and a fifth straight portion (26), the fourth intermediate portion (24) joining the second straight portion (10) and the fifth straight portion (26).

6. Distribution installation (2) according to claim 5, in which the fourth intermediate portion (24) is inclined relative to the second straight portion (10) and in relation to the fifth straight portion (26).

7. Distribution installation (2) according to any one of claims 5 and 6, in which the wall of the second straight portion (10) which is inscribed in the extension plane (P3) extends in a space delimited between a third plane (P4) in which one of the constituent walls of the fifth straight portion (26) is inscribed and a fourth plane (P5) in which another of the constituent walls of the fifth straight portion (26) is inscribed, said walls being opposite each other.

8. Distribution installation (2) according to any one of claims 1 to 7, comprising at least one volume (22) which extends in the first straight portion (8), the second straight portion (10) and the third intermediate portion (12), said volume (22) being delimited by the first plane (PI) and by the extension plane (P3).

9. Distribution installation (2) according to claim 8, in which the volume (22) extends in at least 5% of a passage section of the air flow of the first straight portion (8).

10. Distribution installation (2) according to claim 9, in which the volume (22) extends in the first straight portion (8) in between 10% and 80% of the passage section of the air flow of the first straight portion (8).

11. Distribution installation (2) according to any one of claims 5 to 7, in which the third intermediate portion (12) and the second straight portion (10) form a first bend (30), the second straight portion (10) and the fourth intermediate portion (24) form a second bend (32) and the fourth intermediate portion (24) and the fifth straight portion (26) form a third bend (34), the circulation conduit (4) comprising a succession of assemblies formed from the first bend (30), the second bend (32) and the third bend (34).

12. Distribution installation (2) according to any one of claims 1 to 11, comprising a motor-fan unit (18) configured to circulate the air flow (20) within the circulation duct (4).

13. Distribution installation (2) according to claim 12, in which the third intermediate portion (12) is arranged less than 5 meters from the motor-fan unit (18).

14. Use of a distribution installation (2) for an air flow (20) comprising a circulation duct (4) for the air flow (20), the circulation duct (4) comprising an acoustic attenuation sector (6) configured to limit the propagation of sound waves within the circulation duct (4), the acoustic attenuation sector (6) comprising a plurality of portions (8, 10, 12, 24, 26) of the circulation duct (4), two adjacent portions being inclined relative to each other in order to reduce the propagation of sound waves in the circulation duct (4).

15. Use of a distribution installation (2) for an air flow (20) according to claim 14 in a building, or in a means of transporting people and / or goods.

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