Acoustic treatment device for a ventilation system.

Abstract

Title: Acoustic treatment device for a vehicle cooling system. Acoustic treatment device (1) intended to equip a cooling system of a vehicle and comprising at least one wall (4) participating in delimiting a duct (2) for the circulation of an airflow, 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) 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) disposed in the wall (4) and a neck (22) connecting said 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 different from the value of the corresponding dimension of the other resonators (16) of the row (18). (Figure 3)

Description

Title of the invention: Acoustic treatment device for a ventilation system.

[0001] The present invention falls within the field of vehicle ventilation systems, and more particularly within the field of acoustic treatment devices for such systems, where applicable in a vehicle battery cooling system.

[0002] Vehicle battery cooling systems can be positioned at the front of the vehicle. The front-end modules they form include means for drawing in outside air and a heat exchanger through which the drawn-in air is guided to cool a liquid circulating within the heat exchanger. This liquid is used to cool the batteries within the vehicle's battery pack. The air circulation through such cooling systems is generated by the operation of a ventilation device, and both this operation and the airflow within the system's ducts result in the emission of acoustic waves, which can cause significant noise pollution.

[0003] This noise pollution phenomenon is particularly prevalent in recent electric vehicles, which have large battery packs and can be recharged using fast charging. During fast charging, the batteries heat up rapidly, reaching a significant maximum temperature. To compensate for this heat, the cooling system's ventilation system must operate at very high speeds, resulting in considerable noise outside the vehicle when it is stationary. This noise can also be a nuisance to passengers inside the vehicle who may be present during the battery charging phase.

[0004] It is known to equip systems with ventilation devices with at least one acoustic attenuation device in order to reduce the acoustic energy radiated from said ventilation devices, as illustrated in document FR3083298. This type of acoustic attenuation device includes, for example, a Helmholtz resonator array. This resonator array 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 noise pollution for vehicle occupants.

[0005] This type of acoustic attenuation device is classically implemented to address the problem of absorbing acoustic waves at the interfaces that constitute the walls, in order to attenuate, by dissipative effect, the acoustic energy propagating through a duct of the ventilation system guiding, for example, an airflow towards the passenger compartment of a vehicle.

[0006] However, the front end modules of motor vehicles, which include an air intake and an air intake located on either side of one or more heat exchangers, generate low-frequency waves, between 200 and 1000 Hz, causing significant disturbance to pedestrians. These low frequencies, having a long wavelength, are difficult to treat with conventional acoustic attenuation devices. This difficulty is all the more pronounced when the available volumes are limited, as is the case with the air intakes or intakes of the front end modules. The limited nature of the available volumes is defined by the ratio between the depth available for integrating an attenuation device and the wavelength associated with the frequency of the waves to be treated.

[0007] The present invention aims to improve existing solutions by proposing an acoustic treatment device intended to equip a vehicle cooling system, the acoustic treatment device comprising at least one wall participating in delimiting an airflow circulation duct, said duct being arranged around an axis of elongation parallel to the direction of circulation of an airflow 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 disposed 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 acoustic wave frequencies with a single row of resonators, and therefore in a compact form factor. 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 in turn depend on the available integration volumes. In order to process a target frequency band, the proposed device is equipped with a Helmholtz resonator array positioned in parallel, that is to say, in the same row perpendicular to the direction of wave propagation. Through 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 treatment of acoustic waves of a first frequency, present in the target frequency band, is addressed by the first resonators in the row, having a given dimension, while the treatment of acoustic waves of another frequency, distinct from the first frequency and present in the target frequency band, is addressed by other resonators in the same row but having a different dimension. The acoustic treatment device developed according to the invention thus makes it possible to reduce the perception of a larger frequency bandwidth both outside the vehicle and by the driver and / or passengers inside the passenger compartment.

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

[0011] Here, the term "row" refers to the fact that the resonators are arranged one after the other around a section of the duct viewed in a plane perpendicular to the duct's elongation axis, which defines the direction of acoustic wave propagation. In other words, the resonators in the same row are arranged so that they are crossed by the same plane extending perpendicularly to the duct's elongation axis, or the axis of acoustic wave propagation.

[0012] Furthermore, the term "given dimension" of the resonator is specifically a chosen reference dimension of said resonator, the "corresponding dimension" being the given dimension of said resonator measured on another resonator of the same row. It is understood that, for example, the given dimension is chosen to be the length of the cavity of a resonator, 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 insofar as they go beyond a simple difference due to manufacturing tolerances from one resonator to another. A sizing difference from one resonator to another within the same row, as defined by a feature of the invention, can be observed when this difference affects the acoustic treatment of waves over a frequency range of approximately 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 extension axis of the neck.

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

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

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

[0020] According to another optional feature of the invention, the resonator array 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 is 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 in the resonator array having the same given dimension are arranged one after the other around the duct.

[0021] According to another optional feature 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 in the row of resonators is offset along the elongation axis relative to the necks of the other resonators in the row of resonators.

[0023] Here, it is important to understand, through the concept of axial offset of the necks of resonators in the same row, that a position along the elongation axis of one of the necks associated with a resonator in a given row is different from the position of a Another neck is associated with another resonator in this row, along the elongation axis. This different position reflects a specific offset from the theoretical position of the necks, so it should be understood that the axial offset between two necks of two resonators in the same row according to the invention is greater than a minimal offset due to the manufacturing tolerances of each neck. The axial offset between two necks of two resonators in the same row optimizes the acoustic treatment by implementing a plane wave interference phenomenon.

[0024] According to an optional feature of the invention, the row of resonators comprises at least a first subset of resonators whose necks are traversed by a first plane perpendicular to the elongation axis and a second subset whose necks are traversed by a second plane perpendicular to the elongation axis, the first and second planes being distinct from each other. It should be understood that the cavities of the resonators in the row are centered with respect to each other and that only the neck of some of the resonators, i.e., those forming the aforementioned first subset, are centered. In other words, the system according to the invention consists of a single row of resonators with necks offset from those of a subset of resonators.

[0025] According to another optional feature of the invention, the resonators of the first subset are arranged one after the other, the resonators of the second subset being arranged one after the other.

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

[0027] According to another optional feature 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 feature of the invention, the resonators of the first subset are arranged alternately with the resonators of the second subset.

[0029] The present invention also relates to a front-end module for a vehicle intended to cooperate with a vehicle's ventilation, heating and / or air conditioning system, the front-end module comprising at least one airflow guidance device that helps to define a duct through which air flows The airflow, a ventilation device capable of forcing the circulation of the airflow through the guidance device, a heat exchanger across the guidance 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 guidance device, and that there is continuity between the duct of the acoustic treatment device and the duct of the guidance device.

[0030] Other features, details and advantages of the invention will become clearer upon reading the following description on the one hand, and several illustrative and non-limiting examples of embodiments given with reference to the accompanying schematic drawings on the other hand, in which:

[0031] [Fig-1] is a schematic representation of the front face of a motor vehicle equipped with a front panel 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], one wall of the acoustic treatment device having been removed to make the resonators visible;

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

[0035] [Fig.5] is a cross-section of a variant of the processing device acoustics;

[0036] [Fig.6] is a diagram illustrating the reduction of acoustic energy achieved by the acoustic processing device of the [Fig.3] for acoustic waves with a frequency of 490Hz and for acoustic waves with a frequency of 900Hz;

[0037] [Fig.7] is a diagram allowing a comparison between, on the one hand, the efficiency of the acoustic processing device of [Fig.3], capable of handling acoustic processing of waves of a first frequency of 292Hz and a second frequency of 584Hz, and on the other hand the effectiveness of two prior art acoustic processing devices each separately processing first frequency waves and second frequency waves;

[0038] [Fig.8] is a schematic representation of an alternative embodiment of the invention, and more particularly of a face of the wall delimiting the duct into which the resonators open, making visible an axial offset of the resonators within the same row;

[0039] [Fig.9] is a longitudinal section of a variant of the treatment device acoustics illustrated on [Fig.8];

[0040] [Fig. 10] is a diagram illustrating the acoustic energy reduction achieved by the acoustic treatment device of [Fig.8] for acoustic waves with a frequency of 292Hz and for acoustic waves with a frequency of 584Hz.

[0041] The features, variants, and different embodiments of the invention can be combined in various ways, provided they are not incompatible or mutually exclusive. In particular, variants of the invention may be conceived comprising only a selection of features, described hereafter in isolation from the other described features, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0042] In the figures, the elements common to several figures retain the same reference.

[0043] In the detailed description that 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 principal direction of airflow through the acoustic treatment device and an axis of extension of a duct of the acoustic treatment device, this longitudinal direction being parallel to a longitudinal axis L of an orthonormal L, V, T frame 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 a vertical axis V of the L, V, T frame.

[0044] Figure 1 illustrates 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 airflow guidance device 102 helping to define a duct 2 through which the airflow circulates, a ventilation element 104 capable of forcing the circulation of the airflow through the guidance device, a heat exchanger 106 for the airflow circulating through the guidance device and the acoustic treatment device 1 according to the invention.More specifically, the ventilation unit forces the circulation of an airflow through the device from the external environment of the vehicle through the guidance device, and the heat exchanger is installed through duct 2 and configured to be able to cool a liquid circulating elsewhere within this heat exchanger for the purpose of cooling, in another area of ​​the vehicle, a battery pack.

[0045] The use of the ventilation unit generates acoustic waves at different frequencies, which propagate through the front panel module. The device of Acoustic treatment 1 is configured to attenuate the acoustic energy of sound waves that can be perceived outside the vehicle and / or by a vehicle user. The acoustic treatment device 1 can be arranged, in particular, at the inlet of the front panel module, namely an intake vent 108, or at the outlet of the front panel module, namely an exhaust vent 110.

[0046] Regardless of the position of the acoustic treatment device 1 relative to the guiding device, the acoustic treatment device 1 helps to delimit the duct 2 through which the airflow is forced to circulate. More specifically, and as illustrated in [Fig. 2], the acoustic treatment device 1 comprises at least one wall 4, and more particularly an inner face 6, which helps to delimit at least partially the duct 2 through which the airflow is able to circulate.

[0047] 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 airflow through the duct 2.

[0048] The wall 4 comprises, more specifically, 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 cross-section of the duct 2 delimited by the wall 4, viewed in a plane perpendicular to the elongation axis A, takes on 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. An inlet opening 12 of the duct 2 and an outlet opening 14 of said duct 2 can also be defined, defining the longitudinal dimension of the duct 2 through the acoustic treatment device 1.The terms "inlet" and "outlet" are chosen in particular with regard to the direction of airflow through duct 2.

[0049] In order to process the acoustic energy through the duct 2 of the acoustic treatment device 1, the latter comprises at least one array of resonators 16 formed by one or more rows 18 of resonators 16 arranged in the wall 4 around the duct 2. Each resonator 16 in a row 18 of resonators 16 comprises at least one cavity 20 arranged in the wall 4 and a throat 22 connecting said cavity 20 to the duct 2. The resonators 16 are advantageously Helmholtz resonators. As previously stated, resonators are arranged in the same row 18 when they are arranged around the same section of the duct 2 viewed in a plane perpendicular to the elongation axis A, that is to say, when the same plane, here transverse and vertical, passes through each of these resonators.The various figures in this application illustrate an acoustic treatment device in a compact application, here a front panel module, which involves the . presence of a single row of resonators. But what will be described later also applies to acoustic treatment devices in which several rows of resonators are arranged, provided that at least one of the rows has the characteristics that will be described.

[0050] As mentioned above and 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 conduit 2, the resonators being made visible in these figures by masking the wall delimiting the conduit 2. More particularly, the wall 4 has a thickness measured along a direction perpendicular to the elongation axis A between the inner face 6 of the wall 4 facing the conduit and an opposite outer face 24, and the cavities 20 are arranged within the thickness of the wall 4. The neck 22 of each of the resonators 16 also extends within the thickness of the wall 4, opening on one side into the cavity 20 and on the other side into the conduit 2.

[0051] The cavities 20 take on an overall parallelepiped shape in the wall 4, presenting a substantially rectangular section when viewed in a plane perpendicular to the elongation axis A. The necks 22, for their part, have an overall cylindrical shape with a circular section between the cavity 20 and the conduit 2.

[0052] According to the invention, at least for a given dimension D of the cavity 20 or the neck 22, one or more resonators 16 in the row 18 have a dimension D value different from the corresponding dimension D value of at least one other resonator 16 in the same row 18. The difference in dimension D values ​​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 a different dimension. The acoustic processing device 1 developed according to the invention thus makes it possible to reduce the perception of a wider frequency range of waves by the driver and / or passenger in the passenger compartment.

[0053] Furthermore, at least one resonator 16 in the row 18 of resonators 16 has a given dimension D identical to the corresponding dimension D of its neighboring resonators 16. It is understood that the resonators 16 are not all different from each other within the same row 18, at least with respect to a given dimension D.

[0054] 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 a 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 acoustic energy for this defined number of distinct propagation frequencies.

[0055] Regarding the dimensions D mentioned earlier 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.

[0056] 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.

[0057] 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.

[0058] The length D2 of a cavity 20 corresponds to the greatest distance of the cavity 20 measured along a direction parallel to the elongation axis A of the conduit 2.

[0059] The width D3 of a cavity 20 corresponds to the greatest distance of 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.

[0060] The height D4 of a neck 22 corresponds to the greatest distance of the neck 22 measured along a direction parallel to an extension axis of the neck 22 between an opening of the neck 22 in the cavity 20 and an opening of the neck 22 in the conduit 2.

[0061] The radius D5 of a col 22 corresponds to half of the greatest distance measured along a direction perpendicular to the extension axis of the col 22.

[0062] By way of example, an acoustic processing device according to the invention can be configured so 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.

[0063] In another test, the inventors were able to validate the effectiveness of a device in which a first subgroup 26 of resonators 16, sized to process acoustic waves with a frequency between 250Hz and 300Hz, for example 292Hz, and a second subgroup 28 of resonators 16, sized to process acoustic waves with a frequency between 550Hz and 600Hz, for example 584Hz, are distinguished.

[0064] We will now describe in more detail an example of an embodiment in which the dimensioning of the resonators 16 of the first subgroup 26 is configured to acoustically treat acoustic waves with a frequency of 450Hz, and in which the dimensioning of the resonators 16 of the second subgroup 28 is configured to acoustically treat acoustic waves with a frequency of 900Hz.

[0065] In the following description, the description of the characteristics of a resonator 16 of the first subgroup 26 can be applied to all 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 the resonators 16 of the second subgroup 28.

[0066] 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 80.0mm.

[0067] In this particular example, the resonator 16 of the first subgroup 26 has a first cavity height DI 1 of 20 between 22.0 mm and 24.5 mm. More specifically, the first cavity height DI 1 of the resonator 16 of the first subgroup 26 is 23.5 mm.

[0068] Furthermore, the resonator 16 of the first subgroup 26 has a first cavity width D31 20 between 30.0 mm and 33.5 mm. More specifically, the first cavity width D31 20 of the resonator 16 of the first subgroup 26 is 31.7 mm.

[0069] The resonator 16 of the first subgroup 26 also has a first neck height D41 22 between 1.9 mm and 2.1 mm. More specifically, the first neck height D41 22 of the resonator 16 of the first subgroup 26 is 2.0 mm.

[0070] Finally, the resonator 16 of the first subgroup 26 has a first radius R51 with a neck 22 between 9.0 mm and 10 mm. More specifically, the first radius R51 with a neck 22 of the resonator 16 of the first subgroup 26 is 9.5 mm.

[0071] The dimensioning of the resonator 16 of the second subgroup 28 is distinguished by the fact that it has a second cavity height D12 20 between 34.5 mm and 38.0 mm. More specifically, the second cavity height D12 20 of the resonator 16 of the second subgroup 28 is 36.3 mm.

[0072] Furthermore, the resonator 16 of the second subgroup 28 has a second cavity width D32 20 between 47.5 mm and 52.5 mm. More specifically, the second cavity width D32 20 of the resonator 16 of the second subgroup 28 is 50.0 mm.

[0073] The resonator 16 of the second subgroup 28 also has a second neck height D42 22 between 16.0 mm and 18.0 mm. More specifically, the The second height D42 of the neck 22 of the resonator 16 of the second subgroup 28 is 17.0mm.

[0074] Finally, the resonator 16 of the second subgroup 28 has a second radius D52 with a neck 22 between 9.5 mm and 10.5 mm. More specifically, the second radius D52 with a neck 22 of the resonator 16 of the second subgroup 28 is 10.0 mm.

[0075] As illustrated in [Fig.6], which reflects the amount of attenuated acoustic energy, defined by the ratio between the amount of energy at the input and the amount of energy at the output, as a function of the frequencies of the acoustic waves within the duct equipped with the acoustic treatment device, the dimensioning of the resonators 16 of the first subgroup 26 makes it possible to attenuate acoustic waves with a frequency of 450Hz, in particular here by reducing by about 17dB the acoustic energy of these waves propagating in the duct, while the dimensioning of the resonators 16 of the second subgroup 28 makes it possible to attenuate acoustic waves with a frequency of 900Hz, in particular here by reducing by about 22dB the acoustic energy of these waves propagating in the duct.

[0076] The presence of resonators 16 of the first subgroup 26 and resonators 16 of the second subgroup 28 around the conduit 2 makes it possible to treat both acoustic waves of a first frequency and acoustic waves of a second frequency. The inventors have observed that such combined acoustic treatment makes it possible to effectively treat acoustic waves of two different frequencies, without the effectiveness of the acoustic treatment for each natural frequency being detrimentally reduced. By way of example, [Fig. 7] illustrates in solid lines the amount of acoustic energy reduced with an acoustic treatment device according to the invention, configured to treat in combination acoustic waves of a first frequency of 292 Hz and acoustic waves of a second frequency of 584 Hz.It is noteworthy in this figure that a device specifically configured to process acoustic waves at this first frequency allows for a greater reduction in sound level, as shown in the dotted lines, and that a device specifically configured to process acoustic waves at this second frequency allows for a greater reduction in sound level, as shown in the dashed lines, but the inventors were able to observe that the maximum performance reduction for each frequency is advantageously compensated by the benefit of having a wide range of frequencies efficiently processed by the same acoustic processing device.

[0077] 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 specifically, in this example, the first subgroup 26 is arranged on both one of the vertical panels 8 and one of the transverse panels 10 while the second subgroup 28 is arranged on both the other vertical panel 8 and the other transverse panel 10 of the wall 4.

[0078] According to an alternative embodiment of the invention illustrated in [Fig. 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 faces 8 and the transverse faces 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.

[0079] We will now describe a different functionality that can be implemented in a complementary manner to what has just been described. The resonators 16 in the same row can also be distinguished by their axial positioning within the duct, in addition to their distinction by their dimensions.

[0080] As illustrated in Figures 8 and 9, at least the neck 22 of one of the resonators 16 in the row 18 of resonators 16 is axially offset, along the elongation axis A, relative to the necks 22 of the other resonators 16 in 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 in the row 18 makes it possible to increase the reduction of the sound level, and this in a reduced size, by playing on a phase interference phenomenon, in an assumption of a plane wave field.

[0081] In other words, a position along the elongation axis A of one of the collars 22 is different from the position of another collar 22 along this elongation axis A. For this, at least one of the collars 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 collars 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.

[0082] 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 elongation axis A and a second subset 32 ​​whose necks 22 are crossed by a second plane perpendicular to the elongation axis 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 are aligned the necks 22 of the resonators 16 of the second subset 32 ​​are aligned with each other in relation to each other in relation to the second plane.

[0083] 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.

[0084] A distance d measured along a direction parallel to the elongation axis A between the neck 22 of one of the resonators 16 of the first subassembly 30 and the neck 22 of one of the resonators 16 of the second subassembly 32 is between 30 mm and 80 mm. This distance is measured here along a direction parallel to the elongation axis A between straight lines perpendicular to this elongation axis 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 subassembly 30 and the neck 22 of one of the resonators 16 of the second subassembly 32 could be on the order of 46 mm or on the order of 60 mm. This distance can be a function of the dimensional characteristics of the 16 resonators in the row and / or a function of the frequency of the acoustic waves that we wish to treat.

[0085] Figure 10 schematically illustrates the acoustic gain made possible by a configuration conforming to what has just been described, namely an axial offset of some of the resonator necks relative to other necks in 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 10] illustrates that for each of these distances d and the corresponding frequency of the treated acoustic waves, the gain in acoustic energy reduction is on 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 minimize the transmitted acoustic energy in order to prevent it from being perceived by a vehicle user as well as outside the vehicle.

[0086] In a first configuration, illustrated in [Fig. 8] and visible in [Fig. 2], the resonators 16 of the first subassembly 30 are arranged alternately with the resonators 16 of the second subassembly 32. In other words, at least one resonator 16 of the first subset 30 is framed by two resonators 16 of the second subset 32 ​​and at least one resonator 16 of the second subset 32 ​​is framed by two resonators 16 of the first subset 30.

[0087] Alternatively, and as illustrated in [Fig. 9], the resonators 16 of the first subassembly 30 can be arranged one after the other, and the resonators 16 of the second subassembly 32 are arranged one after the other. In the illustrated example, the resonators 16 of the first subassembly 30 are arranged one after the other by being placed on one of the vertical faces 8, while the resonators 16 of the second subassembly 32 are arranged one after the other on the other vertical face 8. However, it will be understood that the resonators 16 of the first subassembly 30 could also extend over one of the transverse faces 10, while the resonators 16 of the second subassembly 32 could then extend over the other transverse face 10.

[0088] In a variant not illustrated here, the acoustic treatment device 1 according to the invention can be configured such that the resonators 16 of the same row 18 are distributed both in a first subgroup 26 and in a second subgroup 28 as described earlier 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.

[0089] The invention, as described above in several embodiments, achieves its objective, namely, optimizing the reduction of transmitted acoustic energy that can be perceived by the user of a motor vehicle and outside the vehicle, in the application of an acoustic treatment device with resonators arranged in a compact environment. The different sizing of the resonators within the same row advantageously increases the frequency range of acoustic waves that can be effectively treated by the acoustic treatment device and allows for the implementation of an acoustic treatment device with a reduced number of resonator rows.

[0090] The present invention is not limited, however, to the means and configurations described and illustrated herein, and also extends to any equivalent means and configuration as well as to any technically feasible combination of such means. In particular, the examples of sizing and distribution of the resonators 16 in the acoustic treatment device 1 are given as an example and are not limiting to the invention.

Claims

Demands

1. An acoustic treatment device (1) for equipping a vehicle cooling system, the acoustic treatment device (1) comprising at least one wall (4) contributing to the delimitation of an airflow duct (2), said duct (2) being arranged around an axis of elongation (A) parallel to the direction of airflow through the duct (2), the acoustic treatment device (1) comprising at least one array of resonators (16), these resonators (16) being Helmholtz resonators, formed by one or more rows (18) of resonators (16) arranged around the duct (2), the resonators (16) of a single row (18) being arranged so as to be intersected by the same plane extending perpendicularly to the axis of elongation (A), each resonator (16) of a row (18) of resonators (16) comprising at least one cavity (20) disposed in the wall (4) and a neck (22) connecting said cavity (20) to the conduit (2),characterized in that, at least for a given dimension (D, D1, DU, D12, D2, D3, D31, D32, D4, D41, D42, D5, D51, D52) of 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, wherein the given dimension (D, Dl, DU, D12, D2, D3, D31, D32, D4, D41, D42, D5, D51, D52) corresponds to a height (Dl, Dl 1, D12) of the cavity (20) measured along a direction parallel to an extension axis of the neck (22).

3. Acoustic treatment device (1) according to any one of the preceding claims, wherein the given dimension (D, Dl, DU, 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 elongation axis (A) of the duct (2) and to an extension axis of the neck (22).

4. Acoustic treatment device (1) according to any one of the preceding claims, wherein the given dimension (D, D1, DU, 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 extension axis of the neck (22).

5. Acoustic treatment device 1 according to any one of the preceding claims, wherein the dimension (D, D1, DU, 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 extension axis 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 given dimension (D, D1, DU, D12, D2, D3, D31, D32, D4, D41, D42, D5, D51, D52) of a first value and at least a second subgroup (28) of resonators (16) having a second value of the given dimension (D, D1, DU, D12, D2, D3, D31, D32, D4, D41, D42, D5, D51, D52), 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) separate 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 given dimension (D, D1, D12, D2, D3, D31, D32, D4, D41, D42, D5, D51, D52) of a first value and at least a second subgroup (28) of resonators (16) having a second value of the given dimension (D, D1, D12, D2, D3, D31, D32, D4, D41, D42, D5, D51, D52), 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) in the row (18) of resonators (16) is offset along the elongation axis (A) relative to the necks (22) of the other resonators (16) in the row (18) of resonators (16).

9. A front-end module of a vehicle intended to cooperate with a vehicle cooling system, the front-end module comprising at least one airflow guidance device contributing to the delimitation of a duct (2) through which flows the airflow, a ventilation device capable of forcing the circulation of the airflow through the guidance device, a heat exchanger disposed across the guidance device and an acoustic treatment device (1) characterized according to any one of the preceding claims.

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