Device for the acoustic treatment of a ventilation system

Abstract

The invention relates to an acoustic treatment device for a cooling system of a vehicle. The acoustic treatment device (1) is intended to be fitted to a cooling system of a vehicle and comprises at least one wall (4) which participates in delimiting a duct (2) for the circulation of an air flow, the acoustic treatment device (1) comprising at least one array of resonators (16) formed by one or more rows (18) of resonators (16) arranged around the duct (2) perpendicular to an axis of elongation (A) of the duct, each resonator (16) of a row (18) of resonators (16) comprising at least one cavity (20) arranged in the wall (4) and a neck (22) connecting the cavity (20) to the duct (2), characterized in that, at least for a given dimension of the cavity (20) or of the neck (22), at least one resonator (16) of the row (18) has a value that is different from the value of the corresponding dimension of the other resonators (16) of the row (18).

Description

[0001] ACOUSTIC TREATMENT DEVICE FOR A VENTILATION SYSTEM

[0002] The present invention relates to the field of vehicle ventilation systems, and more particularly to the field of acoustic treatment devices for such systems, where appropriate in a vehicle battery cooling system.

[0003] Vehicle battery cooling systems can be positioned on the front of the vehicle. The front modules that they help to form include means for drawing in air from outside the vehicle as well as a heat exchanger through which the air thus drawn in is guided to cool a liquid circulating in the heat exchanger and intended to ensure the cooling of the batteries within the battery pack of the vehicle. The circulation of air through such cooling systems is generated by the operation of a ventilation device and both this operation and the circulation of air within the ducts of the system involve the emission of acoustic waves, which can cause significant noise pollution.

[0004] This noise nuisance phenomenon is even more prevalent in recent electric vehicles, which have large battery packs and can be recharged by rapid charging operations. During rapid charging of the batteries, the latter quickly rise in temperature and the maximum temperature reached is significant. In order to compensate for this heating, the ventilation device of the cooling system must operate at very high rotation speed, which causes significant noise pollution outside the vehicle when stationary. This nuisance can also cause inconvenience to passengers in the passenger compartment who may be present during the battery charging phase.

[0005] It is known to equip systems equipped with ventilation devices with at least one acoustic attenuation device in order to reduce the acoustic energy radiated at the outlet of said ventilation devices, as illustrated in document FR3083298. This type of acoustic attenuation device comprises, for example, a network of Helmholtz resonators. This network of resonators is configured in size and shape to dissipate a maximum of acoustic energy in order to prevent the operation of the cooling system from causing environmental noise pollution and / or for vehicle users. This type of acoustic attenuation device is conventionally implemented in a problem of absorption of acoustic waves at the interfaces constituted by the walls, in order to attenuate, by dissipative effect, the acoustic energy propagating through a duct of the ventilation installation guiding, for example, an air flow towards the passenger compartment of a vehicle.

[0006] However, motor vehicle front end modules, which include a blower vent and a suction vent arranged on either side of one or more heat exchangers, generate low-frequency waves, between 200 and 1000 Hz, causing significant discomfort for pedestrians. These low frequencies, having a long wavelength, are difficult to treat with conventional acoustic attenuation devices. This difficulty is all the greater when the available volumes are restricted, which is the case for the suction or blower vents of the front end modules, the restricted nature of the available volumes being defined by the ratio between the depth available to integrate an attenuation device and the wavelength linked to the frequency of the waves to be treated.

[0007] The present invention aims to improve the already existing solutions by proposing an acoustic treatment device intended to equip a cooling system of a vehicle, the acoustic treatment device comprising at least one wall participating in delimiting a duct for circulation of an air flow, said duct being arranged around an axis of elongation parallel to the direction of circulation of an air flow through the duct, the acoustic treatment device comprising at least one network of resonators formed by one or more rows of resonators arranged around the duct, each resonator of a row of resonators comprising at least one cavity arranged in the wall and a neck connecting said cavity to the duct, characterized in that, at least for a given dimension of the cavity or the neck, at least one resonator of the row has a value different from the value of the corresponding dimension of the other resonators of the row.

[0008] The acoustic processing device according to the invention makes it possible to process several frequencies of acoustic waves with a single row of resonators, and therefore in a reduced footprint. The acoustic processing device thus makes it possible to process acoustic waves over a given frequency bandwidth. This frequency bandwidth will depend on the limits imposed by physics which depend on the available integration volumes. In order to process a target frequency band, the proposed device is equipped with a Helmholtz resonator network positioned in parallel, in other words on the same row perpendicular to the direction of propagation of the waves. From an optimization process, some of the resonators in the same row are sized differently from the others to attenuate the waves over the target frequency band.

[0009] The processing of acoustic waves of a first frequency, present in the target frequency band, is targeted by first resonators of the row, having a given dimensioning, while the processing of acoustic waves of another frequency distinct from the first frequency and present in the target frequency band is targeted by other resonators of the same row and having another dimensioning. The acoustic processing device developed according to the invention thus makes it possible to reduce the perception of a greater frequency bandwidth both outside the vehicle and by the driver and / or passengers present in the passenger compartment.

[0010] The resonators may in particular be Helmholtz resonators. The resonators are, in the acoustic treatment device of the invention, arranged around the duct in one or more rows, the characteristic of the invention according to which resonators of the same row have different dimensions from one resonator to another being able to be applied to one or to each of the rows.

[0011] Here, the term "row" means that the resonators are arranged one after the other around a section of the duct seen in a plane perpendicular to the axis of elongation of the duct, which defines the direction of propagation of the acoustic waves. In other words, the resonators of the same row are arranged so as to be crossed by the same plane extending perpendicular to the axis of elongation of the duct, or axis of propagation of the acoustic waves.

[0012] Furthermore, the term "given dimension" of the resonator is in particular a chosen reference dimension of said resonator, the "corresponding dimension" corresponding to the given dimension of said resonator measured on another resonator of the same row. It is understood that, for example, the length of the cavity of a resonator is chosen as the given dimension, the corresponding dimension on another resonator being the length of the cavity of said other resonator, the two lengths being different from each other.

[0013] Furthermore, two dimensions are different within the meaning of the invention to the extent that they go beyond a simple deviation due to a manufacturing clearance from one resonator to another. A dimensioning differential from one resonator to another can be observed within the same row, as it is the subject of a characteristic of the invention, since this differential has an effect on the acoustic processing of waves over a frequency range of the order of 3 to 4 Hz.

[0014] According to an optional feature of the invention, the given dimension corresponds to a height of the cavity measured along a direction parallel to an axis of extension of the neck.

[0015] According to another optional characteristic of the invention, the given dimension corresponds to a width of the cavity measured along a direction perpendicular to the axis of elongation of the conduit and to an axis of extension of the neck.

[0016] According to another optional characteristic of the invention, the given dimension corresponds to a length of the cavity measured along a direction parallel to the axis of elongation of the conduit.

[0017] According to another optional feature of the invention, the given dimension corresponds to a height of the neck measured along a direction parallel to an axis of extension of the neck.

[0018] According to another optional feature of the invention, the dimension corresponds to a radius of the neck measured along a direction perpendicular to the axis of extension of the neck.

[0019] According to another optional feature of the invention, at least one resonator of the row of resonators has a given dimension identical to the corresponding dimension of these neighboring resonators. It is understood that the resonators are not all different from each other within the same row.

[0020] According to another optional characteristic of the invention, the row of resonators comprises a first subgroup of resonators having a given dimension of a first value and at least a second subgroup of resonators having a second value of the given dimension, different from the first value, the first subgroup of resonators being arranged on a first portion of the acoustic treatment device while the second subgroup of resonators is arranged on a second portion of the acoustic treatment device distinct from the first portion. It is understood that the resonators of the row of resonators having the same given dimension are arranged one after the other around the duct.

[0021] According to another optional characteristic of the invention, the row of resonators comprises a first subgroup of resonators having a given dimension of a first value and at least a second subgroup of resonators having a second value of the given dimension, different from the first value, the resonators of the first subgroup of resonators being arranged alternately with the resonators of the second subgroup of resonators.

[0022] According to another optional feature of the invention, at least the neck of one of the resonators of the row of resonators is offset along the elongation axis relative to the necks of the other resonators of the row of resonators.

[0023] Here, it is appropriate to understand, by the notion of axial offset of the necks of resonators of the same row, that a position along the elongation axis of one of the necks associated with a resonator of a given row is different from the position of another neck associated with another resonator of this row, along the elongation axis. This different position reflects a determined offset of the theoretical position of the necks, so that it is appropriate to understand that the axial offset between two necks of two resonators of the same row according to the invention is greater than a minimal offset due to the manufacturing tolerances of each of the necks. The axial offset between two necks of two resonators of the same row makes it possible to optimize the acoustic treatment, by implementing an interference phenomenon of a plane wave field.

[0024] According to an optional characteristic of the invention, the row of resonators comprises at least a first subset of resonators whose necks are crossed by a first plane perpendicular to the axis of elongation and a second subset whose necks are crossed by a second plane perpendicular to the axis of elongation, the first plane and the second plane being distinct from each other. It should be understood that the cavities of the resonators of the row are centered relative to each other and that only the neck of some of the resonators, that is to say those forming the first subset mentioned. In other words, in the system according to the invention there is indeed a single row of resonators with offset necks of a subset of resonators.

[0025] According to another optional characteristic of the invention, the resonators of the first sub-assembly are arranged one after the other, the resonators of the second sub-assembly being arranged one after the other.

[0026] According to another optional characteristic of the invention, the duct is open to an inlet opening of an air flow and to an outlet opening of an air flow, the necks of the resonators of the first subset of resonators being arranged closer to the inlet opening of the duct than to the outlet opening of the duct, while the necks of the resonators of the second subset of resonators are arranged closer to the outlet opening of the duct than to the inlet opening of the duct.

[0027] According to another optional characteristic of the invention, the resonators of the first sub-assembly are arranged on a first face of the wall opposite a second face of the wall on which the resonators of the second sub-assembly are arranged.

[0028] According to another optional characteristic of the invention, the resonators of the first sub-assembly are arranged alternately with the resonators of the second sub-assembly.

[0029] The present invention also relates to a front end module of a vehicle intended to cooperate with a ventilation, heating and / or air conditioning system of a vehicle, the front end module comprising at least one device for guiding an air flow participating in delimiting a duct through which the air flow circulates, a ventilation member capable of forcing the circulation of the air flow through the guiding device, a heat exchanger across the guiding device and an acoustic treatment device characterized according to any one of the preceding characteristics. It is understood here that the acoustic treatment device forms all or part of the guiding device, and that there is continuity between the duct of the acoustic treatment device and the duct of the guiding device.

[0030] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and several examples of embodiment given for informational and non-limiting purposes with reference to the appended schematic drawings on the other hand, in which:

[0031] [Fig. 1] is a schematic representation of a front face of a motor vehicle equipped with a front face module in which an acoustic treatment device according to the invention is mounted;

[0032] [Fig. 2] is a perspective representation of a first embodiment of the acoustic treatment device according to the invention;

[0033] [Fig. 3] is a perspective representation of the resonators and a duct of the acoustic treatment device illustrated in Fig. 2, with one wall of the acoustic treatment device removed to expose the resonators;

[0034] [Fig. 4] is a cross-section of the acoustic treatment device illustrated in Fig. 3; [Fig. 5] is a cross-section of a variant of the acoustic treatment device;

[0035] [Fig. 6] is a diagram illustrating the acoustic energy reduction achieved by the acoustic treatment device of Figure 3 for acoustic waves of a frequency of 490Hz and for acoustic waves of a frequency of 900Hz;

[0036] [Fig. 7] is a diagram allowing a comparison between, on the one hand, the efficiency of the acoustic processing device of Figure 3, capable of managing acoustic processing of waves of a first frequency of 292 Hz and a second frequency of 584 Hz, and on the other hand the efficiency of two acoustic processing devices of the prior art each processing separately the waves of the first frequency and the waves of the second frequency;

[0037] [Fig. 8] is a schematic representation of an alternative embodiment of the invention, and more particularly of a face of the wall delimiting the conduit into which the resonators open, making visible an axial offset of the resonators within the same row;

[0038] [Fig. 9] is a longitudinal section of a variant of the acoustic treatment device illustrated in Fig. 8;

[0039] [Fig. 10] is a diagram illustrating the acoustic energy reduction achieved by the acoustic treatment device of Figure 8 for acoustic waves with a frequency of 292Hz and for acoustic waves with a frequency of 584Hz.

[0040] 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 conceived 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 and / or to differentiate the invention from the prior art.

[0041] In the figures, elements common to several figures retain the same reference.

[0042] In the detailed description which follows, the terms “longitudinal”, “transverse” and “vertical” refer to the orientation of an acoustic treatment device according to the invention. A longitudinal direction corresponds to a main direction of circulation of an air flow through the acoustic treatment device and an axis of elongation of a duct of the acoustic treatment device, this longitudinal direction being parallel to a longitudinal axis L of an orthonormal reference frame L, V, T illustrated in the figures. A transverse direction and a vertical direction correspond to directions perpendicular to the longitudinal direction, respectively parallel to a transverse axis T and to a vertical axis V of the reference frame L, V, T.

[0043] In Figure 1 is illustrated an acoustic treatment device 1 according to the invention configured to be installed within a front panel module 100 of a vehicle 101. Such a front panel module 100 comprises for example at least one device 102 for guiding an air flow participating in delimiting a duct 2 through which the air flow circulates, a ventilation member 104 capable of forcing the circulation of the air flow through the guide device, a heat exchanger 106 for the air flow circulating through the guide device and the acoustic treatment device 1 according to the invention.More particularly, the ventilation member forces the circulation of an air flow through the device from the external environment of the vehicle through the guide device, and the heat exchanger is installed through the conduit 2 and configured to be able to cool a liquid circulating elsewhere within this heat exchanger for the purpose of cooling, in another zone of the vehicle, a battery pack.

[0044] The use of the ventilation member generates acoustic waves at different frequencies, which propagate through the front panel module. The acoustic treatment device 1 is configured to attenuate the acoustic energy of the acoustic waves which can be perceived outside the vehicle and / or by a user of the vehicle. The acoustic treatment device 1 may in particular be arranged at the inlet of the front panel module, namely a suction vent 108, or at the outlet of the front panel module, namely a blower vent 110.

[0045] Regardless of the position of the acoustic treatment device 1 relative to the guide device, the acoustic treatment device 1 participates in delimiting the duct 2 through which the air flow is forced to circulate. More particularly, and as illustrated in FIG. 2, the acoustic treatment device 1 comprises at least one wall 4, and more particularly an internal face 6, which participates in delimiting at least in part the duct 2 through which the air flow is able to circulate.

[0046] The inner face 6 of the wall 4 is configured so as to delimit the duct 2 around an elongation axis A extending parallel to the direction of circulation of the air flow through the duct 2. The wall 4 more particularly comprises four sections, including two transverse sections 10 and two vertical sections 8 extending respectively in planes substantially perpendicular to the planes in which the transverse sections 10 are inscribed, the inner face of the wall being defined by the successive inner faces of the different sections. The sections are arranged so that a section of the duct 2 delimited by the wall 4 seen in a plane perpendicular to the elongation axis A takes a generally rectangular shape delimited transversely by the inner faces 6 of the transverse sections 10 and vertically by the inner faces 6 of the vertical sections 8.It is also possible to define an inlet opening 12 of the duct 2 and an outlet opening 14 of said duct 2 defining the longitudinal dimension of the duct 2 through the acoustic treatment device 1. The terms “inlet” and “outlet” are notably chosen with respect to the direction of circulation of the air flow through the duct 2.

[0047] In order to process the acoustic energy through the conduit 2 of the acoustic processing device 1, the latter comprises at least one network of resonators 16 formed by one or more rows 18 of resonators 16 arranged in the wall 4 around the conduit 2. Each resonator 16 of a row 18 of resonators 16 comprises at least one cavity 20 arranged in the wall 4 and a neck 22 connecting said cavity 20 to the conduit 2. The resonators 16 are advantageously Helmholtz resonators. As previously specified, resonators are arranged in the same row 18 when they are arranged around the same section of the conduit 2 seen in a plane perpendicular to the axis of elongation A, that is to say when the same plane, here transverse and vertical, passes through each of these resonators.The various figures of the present application illustrate an acoustic treatment device in a space-saving application, here a front panel module, which involves the presence of a single row of resonators. But what will be described subsequently is also suitable for acoustic treatment devices in which several rows of resonators are arranged, provided that at least one of the rows has the characteristics which will be described.

[0048] As mentioned above and as illustrated in Figures 3 to 5, 8 and 9, each of the resonators comprises a cavity 20 and a neck 22 connecting the cavity 20 to the duct 2, the resonators being made visible in these figures by the masking of the wall delimiting the duct 2. More particularly, the wall 4 has a thickness measured along a direction perpendicular to the axis of elongation A between the internal face 6 of the wall 4 facing the duct and an opposite external face 24, and the cavities 20 are arranged in the thickness of the wall 4. The neck 22 of each of the resonators 16 also extends in the thickness of the wall 4, opening on the one hand into the cavity 20 and on the other hand into the duct 2.

[0049] The cavities 20 take a generally parallelepiped shape in the wall 4, presenting a substantially rectangular section seen in a plane perpendicular to the axis of elongation A. The necks 22 present a generally cylindrical shape of circular section between the cavity 20 and the conduit 2.

[0050] According to the invention, at least for a given dimension D of the cavity 20 or the neck 22, one or more resonators 16 of the row 18 have a dimension value D different from the corresponding dimension value D of at least one other resonator 16 of the same row 18. The difference in values ​​of the dimension D from one resonator to another within the same row 18 makes it possible to process acoustic waves at two different frequencies, the acoustic waves of a first frequency being for example processed mainly by the resonators 16 of a given dimension, while the acoustic waves of a second frequency distinct from the first frequency are processed mainly by a resonator 16 of another dimension. The acoustic processing device 1 developed according to the invention thus makes it possible to reduce the perception of a larger frequency range of waves by the driver and / or the passenger present in the passenger compartment.

[0051] Furthermore, at least one resonator 16 of the row 18 of the resonators 16 has a given dimension D identical to the corresponding dimension D of these neighboring resonators 16. It is understood that the resonators 16 are not all different from each other within the same row 18, at least according to a given dimension D.

[0052] It can thus be defined that the row 18 of resonators 16 comprises a first subgroup 26 of resonators 16 having a given dimension D of a first value and at least one second subgroup 28 of resonators 16 having a second value of the given dimension D, different from the first value. More generally, according to the invention, the resonators 16 can be grouped into a defined number of subgroups to process the acoustic energy for this defined number of distinct propagation frequencies.

[0053] With regard to the dimensions D mentioned previously in the description, the term “given dimension D” of the resonator 16 is in particular a chosen reference dimension D of said resonator 16, the “corresponding dimension D” corresponding to the given dimension D of said resonator 16 measured on another resonator 16 of the same row 18. It is understood that, for example, the length D2 of the cavity 20 of a resonator 16 is chosen as the given dimension D, the corresponding dimension D on another resonator 16 being the length D2 of the cavity 20 of said other resonator 16, the two lengths D2 being different from each other.

[0054] The given dimension D can be chosen from a height DI of the cavity 20, a length D2 of the cavity 20, a width D3 of the cavity 20, a height D4 of the neck 22 and / or a radius D5 of the neck 22, this list not being exhaustive.

[0055] The height DI of a cavity 20 corresponds to the greatest distance of the cavity 20 measured along a direction parallel to an extension axis of the neck 22.

[0056] The length D2 of a cavity 20 corresponds to the greatest distance from the cavity 20 measured along a direction parallel to the axis of elongation A of the conduit 2.

[0057] The width D3 of a cavity 20 corresponds to the greatest distance from the cavity 20 measured along a direction perpendicular to the elongation axis A of the conduit 2 and to an extension axis of the neck 22.

[0058] The height D4 of a neck 22 corresponds to the greatest distance of the neck 22 measured along a direction parallel to an axis of extension of the neck 22 between an outlet of the neck 22 in the cavity 20 and an outlet of the neck 22 in the conduit 2.

[0059] The radius D5 of a neck 22 corresponds to half of the greatest distance measured along a direction perpendicular to the axis of extension of the neck 22.

[0060] By way of example, an acoustic processing device according to the invention can be configured such that the first subgroup 26 of resonators 16 can process acoustic waves whose frequency is between 400Hz and 500Hz, for example 450Hz, the second subgroup 28 of resonators 16 being able to process acoustic waves whose frequency is between 850Hz and 950Hz, for example 900Hz.

[0061] In another test, the inventors were able to validate the effectiveness of a device in which a first subgroup 26 of resonators 16 is distinguished, sized to process acoustic waves whose frequency is between 250Hz and 300Hz, for example 292Hz, and a second subgroup 28 of resonators 16, sized to process acoustic waves whose frequency is between 550Hz and 600Hz, for example 584Hz. An exemplary embodiment will now be described in more detail in which the sizing of the resonators 16 of the first subgroup 26 is configured to acoustically process acoustic waves having a frequency of 450Hz, and in which the sizing of the resonators 16 of the second subgroup 28 is configured to acoustically process acoustic waves having a frequency of 900Hz.

[0062] In the remainder of the description, the description of the characteristics of a resonator 16 of the first subgroup 26 can be applied to all of the resonators 16 of the first subgroup 26. Equivalently, the description of the characteristics of a resonator 16 of the second subgroup 28 can be applied to all of the resonators 16 of the second subgroup 28.

[0063] Here, the length D2 of the resonators 16 of the first subgroup 26 and of the resonators 16 of the second subgroup 28 is identical and equal to 80.0 mm.

[0064] In this particular example, the resonator 16 of the first subgroup 26 has a first height DU of cavity 20 of between 22.0 mm and 24.5 mm. More particularly, the first height DU of cavity 20 of the resonator 16 of the first subgroup 26 is 23.5 mm.

[0065] In addition, the resonator 16 of the first subgroup 26 has a first width D31 of cavity 20 of between 30.0 mm and 33.5 mm. More particularly, the first width D31 of cavity 20 of the resonator 16 of the first subgroup 26 is 31.7 mm.

[0066] The resonator 16 of the first subgroup 26 also has a first height D41 of neck 22 of between 1.9 mm and 2.1 mm. More particularly, the first height D41 of neck 22 of the resonator 16 of the first subgroup 26 is 2.0 mm.

[0067] Finally, the resonator 16 of the first subgroup 26 has a first radius R51 of neck 22 of between 9.0 mm and 10 mm. More particularly, the first radius R51 of neck 22 of the resonator 16 of the first subgroup 26 is 9.5 mm.

[0068] The dimensioning of the resonator 16 of the second subgroup 28 is distinguished in that it has a second height D12 of cavity 20 of between 34.5 mm and 38.0 mm. More particularly, the second height D12 of cavity 20 of the resonator 16 of the second subgroup 28 is 36.3 mm. In addition, the resonator 16 of the second subgroup 28 has a second width D32 of cavity 20 of between 47.5 mm and 52.5 mm. More particularly, the second width D32 of cavity 20 of the resonator 16 of the second subgroup 28 is 50.0 mm.

[0069] The resonator 16 of the second subgroup 28 also has a second height D42 of neck 22 of between 16.0 mm and 18.0 mm. More particularly, the second height D42 of neck 22 of the resonator 16 of the second subgroup 28 is 17.0 mm.

[0070] Finally, the resonator 16 of the second subgroup 28 has a second radius D52 of neck 22 of between 9.5 mm and 10.5 mm. More particularly, the second radius D52 of neck 22 of the resonator 16 of the second subgroup 28 is 10.0 mm.

[0071] As illustrated in Figure 6, which reflects the quantity of attenuated acoustic energy, defined by the ratio between the quantity of input energy and the quantity of output energy, as a function of the frequencies of the acoustic waves within the duct equipped with the acoustic treatment device, the sizing of the resonators 16 of the first subgroup 26 makes it possible to attenuate acoustic waves with a frequency of 450 Hz, in particular here by reducing by approximately 17 dB the acoustic energy of these waves propagating in the duct, while the sizing of the resonators 16 of the second subgroup 28 makes it possible to attenuate acoustic waves with a frequency of 900 Hz, in particular here by reducing by approximately 22 dB the acoustic energy of these waves propagating in the duct.

[0072] The presence of resonators 16 of the first subgroup 26 and of resonators 16 of the second subgroup 28 around the conduit 2 makes it possible to process both acoustic waves of a first frequency and acoustic waves of a second frequency. The inventors have been able to observe that such combined acoustic treatment makes it possible to effectively process acoustic waves of two different frequencies, without the effectiveness of the acoustic treatment for each natural frequency being detrimentally reduced. As an example, Figure 7 illustrates in solid lines the quantity of acoustic energy reduced with an acoustic treatment device according to the invention, configured to process in a combined manner acoustic waves of a first frequency of 292 Hz and acoustic waves of a second frequency of 584 Hz.It is notable in this figure that a device specifically configured to process the acoustic waves at this first frequency makes it possible to reduce the sound level more significantly, as is visible in dotted lines, and that a device specifically configured to process the acoustic waves at this second frequency makes it possible to reduce the sound level more significantly, as is visible in mixed lines, but the inventors were able to observe that the reduced maximum performance for each frequency is advantageously compensated by the benefit of having a wide range of frequencies processed effectively by the same acoustic processing device.

[0073] In the example illustrated in Figures 3 and 4, the resonators 16 of the row 18 of resonators 16 having the same given dimension D are arranged one after the other around the duct 2. The first subgroup 26 of resonators 16 is thus arranged on a first portion of the acoustic treatment device 1 while the second subgroup 28 of resonators 16 is arranged on a second portion of the acoustic treatment device 1 distinct from the first portion. More particularly, in this example, the first subgroup 26 is arranged both on one of the vertical sections 8 and one of the transverse sections 10 while the second subgroup 28 is arranged both on the other vertical section 8 and the other transverse section 10 of the wall 4.

[0074] According to an alternative example of the invention illustrated in Figure 5, the resonators 16 of the first subgroup 26 of resonators 16 are arranged alternately with the resonators 16 of the second subgroup 28 of resonators 16. It is understood that the resonators 16 of the first subgroup 26 and the resonators 16 of the second subgroup 28 are arranged on each of the vertical sections 8 and the transverse sections 10 of the wall 4 so that at least one resonator 16 of the first subgroup 26 is framed by two resonators 16 of the second subgroup 28, and that at least one resonator 16 of the second subgroup 28 is framed by two resonators 16 of the first subgroup 26.

[0075] We will now describe a different functionality which can be implemented in a complementary manner to what has just been described. The resonators 16 of the same row can also be distinguished by their axial positioning within the duct, in a complementary manner to their distinction by their dimensioning.

[0076] As illustrated in Figures 8 and 9, at least the neck 22 of one of the resonators 16 of the row 18 of resonators 16 is axially offset, along the elongation axis A, relative to the necks 22 of the other resonators 16 of the same row 18, by a distance d. The longitudinal axial offset of the neck 22 of at least one of the resonators 16 relative to the necks 22 of the other resonators 16 of the row 18 makes it possible to increase the reduction in the sound level, and this in a reduced size, by playing on a phase interference phenomenon, in a plane wave field hypothesis. In other words, a position along the elongation axis A of one of the necks 22 is different from the position of another neck 22 along this elongation axis A.For this, at least one of the necks 22 of the row 18 of resonators 16 is closer to the inlet opening 12 than to the outlet opening 14 of the conduit 2, and / or at least one of the other necks 22 of the row 18 of resonators 16 is closer to the outlet opening 14 than to the inlet opening 12 of the conduit 2.

[0077] It can thus be defined that the row 18 of resonator 16 comprises at least a first subset 30 of resonators 16 whose necks 22 are crossed by a first plane perpendicular to the axis of elongation A and a second subset 32 ​​whose necks 22 are crossed by a second plane perpendicular to the axis of elongation A, the first plane and the second plane being distinct from each other. It is understood that the necks 22 of the resonators 16 of the first subset 30 align with each other by being inscribed in the first plane while the necks 22 of the resonators 16 of the second subset 32 ​​align with each other by being inscribed in the second plane.

[0078] In the example illustrated and visible in Figures 8 and 9, the necks 22 of the resonators 16 of the first subassembly 30 are arranged closer to the inlet opening 12 of the conduit 2 than to the outlet opening 14 of the conduit 2, and the necks 22 of the resonators 16 of the second subassembly 32 are arranged closer to the outlet opening 14 of the conduit 2 than to the inlet opening 12 of the conduit 2.

[0079] A distance d measured along a direction parallel to the axis of elongation A between the neck 22 of one of the resonators 16 of the first sub-assembly 30 and the neck 22 of one of the resonators 16 of the second sub-assembly 32 is between 30 mm and 80 mm. This distance is here measured along a direction parallel to the axis of elongation A between straight lines perpendicular to this axis of elongation A and passing through the centers of the two necks 22. By way of example, such a distance measured between the neck 22 of one of the resonators 16 of the first sub-assembly 30 and the neck 22 of one of the resonators 16 of the second sub-assembly 32 may be of the order of 46 mm or of the order of 60 mm. This distance may be a function of the dimensional characteristics of the resonators 16 of the row and / or a function of the frequency of the acoustic waves that one wishes to process.

[0080] Figure 10 schematically illustrates the acoustic gain made possible by a configuration in accordance with what has just been described, namely an axial offset of some of the resonator necks relative to other necks of the same row of resonators. The inventors were able to determine by calculation that, for resonators arranged in a front panel module and configured to process acoustic waves with a frequency of 292 Hz, a distance d between the two subsets of resonators can advantageously be equal to 60 mm, and that for resonators arranged in a front panel module and configured to process acoustic waves with a frequency of 584 Hz, a distance d between the two subsets of resonators can advantageously be equal to 46 mm. Figure 10 illustrates that for each of these distances d and the corresponding frequency of the processed acoustic waves, the gain in reduction of the acoustic energy is of the order of 20 to 30%.It is understood that for other acoustic wave frequencies, this distance d would be mathematically determined by the inventors to be optimal and to reduce as much as possible the transmitted acoustic energy in order to prevent it from being perceived by a user of the vehicle as well as outside the vehicle.

[0081] In a first configuration, illustrated in Figure 8 and visible in Figure 2, the resonators 16 of the first sub-assembly 30 are arranged alternately with the resonators 16 of the second sub-assembly 32. In other words, at least one resonator 16 of the first sub-assembly 30 is framed by two resonators 16 of the second sub-assembly 32 and at least one resonator 16 of the second sub-assembly 32 is framed by two resonators 16 of the first sub-assembly 30.

[0082] Alternatively and as illustrated in Figure 9, the resonators 16 of the first sub-assembly 30 can be arranged one after the other, and the resonators 16 of the second sub-assembly 32 are arranged one after the other. In the illustrated example, the resonators 16 of the first sub-assembly 30 are arranged one after the other by being arranged on one of the vertical sections 8 while the resonators 16 of the second sub-assembly 32 are arranged one after the other on the other vertical section 8, but it will be understood that the resonators 16 of the first sub-assembly 30 could also extend over one of the transverse sections 10 while the resonators 16 of the second sub-assembly 32 could then extend over the other transverse section 10.

[0083] In a variant not illustrated here, the acoustic treatment device 1 according to the invention can be configured so that the resonators 16 of the same row 18 are distributed both in a first subgroup 26 and in a second subgroup 28 like those described previously in the description, and in a first subset 30 and in a second subset 32 ​​as described above. It is understood that the same resonator 16 constitutes both one of the subgroups and one of the subsets. A resonator 16 can thus constitute the first subgroup 26 and the first subset 30 or the second subset 32, or the second subgroup 28 and the first subset 30 or the second subset 32.

[0084] The invention as just described through several embodiments makes it possible to achieve the goal it set for itself, namely the optimization of the reduction of acoustic energy transmitted and likely to be perceived by the user of a motor vehicle as well as outside the vehicle, in an application of an acoustic treatment device with resonators arranged in an environment with reduced bulk.

[0085] The different sizing of the resonators within the same row of resonators advantageously makes it possible to increase the frequency range of the acoustic waves capable of being effectively processed by the acoustic treatment device and allows the implementation of an acoustic treatment device with a reduced number of rows of resonators.

[0086] 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. In particular, the examples of dimensioning and distribution of the resonators 16 in the acoustic treatment device 1 are given for information purposes only and are not limiting of the invention.

Claims

CLAIMS 1. Acoustic treatment device (1) intended to equip a cooling system of a vehicle, the acoustic treatment device (1) comprising at least one wall (4) participating in delimiting a duct (2) for circulation of an air flow, said duct (2) being arranged around an elongation axis (A) parallel to the direction of circulation of an air flow through the duct (2), the acoustic treatment device (1) comprising at least one network of resonators (16) formed by one or more rows (18) of resonators (16) arranged around the duct (2), each resonator (16) of a row (18) of resonators (16) comprising at least one cavity (20) arranged in the wall (4) and a neck (22) connecting said cavity (20) to the duct (2), characterized in that, at least for one dimension (D, DI, Dll, D12, D2, D3, D31, D32, D4, D41, D42, D5, D51, D52) given from the cavity (20) or the neck (22),at least one resonator (16) of the row (18) has a value different from the value of the corresponding dimension of the other resonators (16) of the row (18)., 2. Acoustic treatment device (1) according to the preceding claim, in which the given dimension (D, DI, Dll, D12, D2, D3, D31, D32, D4, D41, D42, D5, D51, D52) corresponds to a height (DI, Dll, D12) of the cavity (20) measured along a direction parallel to an axis of extension of the neck (22).

3. Acoustic treatment device (1) according to any one of the preceding claims, in which the given dimension (D, DI, Dll, D12, D2, D3, D31, D32, D4, D41, D42, D5, D51, D52) corresponds to a width (D3, D31, D32) of the cavity (20) measured along a direction perpendicular to the axis of elongation (A) of the duct (2) and to an axis of extension of the neck (22).

4. Acoustic treatment device (1) according to any one of the preceding claims, wherein the given dimension (D, DI, Dll, D12, D2, D3, D31, D32, D4, D41, D42, D5, D51, D52) corresponds to a height (D4, D41, D42) of the neck (22) measured along a direction parallel to an axis of extension of the neck (22).

5. Acoustic treatment device 1 according to any one of the preceding claims, wherein the dimension (D, DI, Dll, D12, D2, D3, D31, D32, D4, D41, D42, D5, D51, D52) corresponds to a radius (D5, D51, D52) of the neck (22) measured along a direction perpendicular to the axis of extension of the neck (22).

6. Acoustic treatment device (1) according to any one of the preceding claims, wherein the row (18) of resonators (16) comprises a first subgroup (26) of resonators (16) having a dimension (D, DI, D1, D12, D2, D3, D31, D32, D4, D41, D42, D5, D51, D52) given a first value and at least a second subgroup (28) of resonators (16) having a second value of the dimension (D, DI, Dl l, D12, D2, D3, D31, D32, D4, D41, D42, D5, D51, D52) given, different from the first value, the first subgroup (26) of resonators (16) being arranged on a first portion of the acoustic treatment device (1) while the second subgroup (28) of resonators (16) is arranged on a second portion of the acoustic treatment device (1) distinct from the first portion.

7. Acoustic treatment device (1) according to any one of claims 1 to 5, wherein the row (18) of resonators (16) comprises a first subgroup (26) of resonators (16) having a dimension (D, D1, D11, D12, D2, D3, D31, D32, D4, D41, D42, D5, D51, D52) given by a first value and at least one second subgroup (28) of resonators (16) having a second value of the dimension (D, D1, D11, D12, D2, D3, D31, D32, D4, D41, D42, D5, D51, D52) given, different from the first value, the resonators (16) of the first subgroup (26) of resonators (16) being arranged alternately with the resonators (16) of the second ... subgroup (28) of resonators (16).

8. Acoustic treatment device (1) according to any one of the preceding claims, wherein at least the neck (22) of one of the resonators (16) of the row (18) of resonators (16) is offset along the elongation axis (A) relative to the necks (22) of the other resonators (16) of the row (18) of resonators (16).

9. Front end module of a vehicle intended to cooperate with a cooling system of a vehicle, the front end module comprising at least one device for guiding an air flow participating in delimiting a duct (2) through which the air flow circulates, a ventilation member capable of forcing the circulation of the air flow through the guide device, a heat exchanger arranged across the guide device and an acoustic treatment device (1) characterized according to any one of the preceding claims.

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