WO2020207693A1

WO2020207693A1 - Unit comprising a casing and subwoofer duct with variable geometry

Info

Publication number: WO2020207693A1
Application number: PCT/EP2020/056613
Authority: WO
Inventors: Matthieu Lemonnier
Original assignee: Renault S.A.S
Priority date: 2019-04-09
Filing date: 2020-03-12
Publication date: 2020-10-15
Also published as: EP3953215A1; FR3094930A1; FR3094930B1

Abstract

The invention relates to a unit (1) comprising: - a casing (2) forming an internal space, a first surface of the casing (2) comprising an opening (3), and a second surface of the casing (2) comprising a port (4), and - a duct (5) for a subwoofer comprising a main portion defined by first and second open ends, the first end being connected to the casing (2), the opening of which corresponds to said port (4), thus forming an input, the second end being configured to lead to the outside, thus forming an output (6), said unit (1) being characterised in that the main portion of the duct (5) has a cross-sectional area the geometry of which varies between the two ends thereof, the first end of the duct having a different geometric shape from the second.

Description

Scalable geometry subwoofer housing and duct assembly

The invention relates to acoustic systems and more specifically to subwoofer conduits. It finds an advantageous application in the form of an assembly comprising a subwoofer conduit with scalable geometry, of an audio system comprising such an assembly and of a motor vehicle equipped with such an audio system.

It is known, in particular from document EP3258703, to make the rear of a loudspeaker communicate with the outside of the passenger compartment of a motor vehicle by an air duct while having a compact subwoofer volume. . This principle is very qualitative in audio performance, and has the advantage of reducing the volume of the subwoofer from around twenty liters for a classic high performance subwoofer against around two liters for a box connected to the outside. Such conduits connecting the interior of the passenger compartment to the exterior of the vehicle body therefore impose a seal.

Also known from document US2018 / 0242076A1 a subwoofer duct which extends in the upper part of the trunk of a vehicle and along one side of the vehicle and connects an air inlet located on top of the trunk and an air outlet located on the side between the rear end of the trunk and the wheel arch. However, the duct is then quite long, which represents a certain space requirement as well as assembly difficulties and does not allow optimum acoustic performance to be achieved.

One of the aims of the invention is to remedy at least part of the drawbacks of the prior art by providing a compact assembly comprising a support box for a loudspeaker and a subwoofer duct with scalable geometry along its main portion. connecting the internal volume of the support box to the outside of the vehicle.

To this end, the invention provides an assembly for a motor vehicle comprising:

a box forming an internal volume, in particular configured to house a loudspeaker, a first face of the box comprising an opening suitable for receiving a loudspeaker, and a second face of the box comprising an orifice configured to receive a duct, and

a conduit for a subwoofer comprising a main portion delimited by a first and a second open ends, the first end being connected to the box and the opening of which corresponds to said orifice forming an inlet, the second end being configured to open towards the exterior of the vehicle forming an outlet, said assembly being characterized in that the main portion of the duct has a passage section whose geometry varies between its two ends, the first end of the duct having a different geometric shape from the second end of the duct. Thanks to the invention, the assembly is adapted to the constrained spaces of automotive architectures.

According to an advantageous characteristic, the second face of the box is substantially perpendicular to the first face, which makes it possible to obtain a shallow audio system (along the Y axis).

According to another advantageous characteristic, the duct stretches along an inclined axis, by at least 20 °, relative to the plane formed by the first face of the box, which makes it possible to position the duct without protruding from the Y grip of the box.

According to another advantageous characteristic, the inlet extends in an inlet plane substantially perpendicular to an outlet plane in which the outlet extends. This characteristic makes it possible to direct the air flow in accordance with the architectural constraints of the vehicle.

According to another advantageous characteristic, the orifice forming the entrance to the first end of the duct has a triangular shape, which allows to have an easily positioned air inlet at the rear of the loudspeaker.

According to another advantageous characteristic, the outlet formed by the second open end of the duct has an ovoid shape, which makes it possible to minimize a fouling potential with respect to an angular shape given the position of this outlet in the wheel arch for example.

According to another advantageous characteristic, the area of the passage section remains constant along the main section between the inlet and the outlet of the duct, which allows a better prediction of the audio performance.

According to another advantageous characteristic, the outer contour of the main portion of the duct has the shape of a quarter-disc in the plane perpendicular to the inlet plane or to the outlet plane, the advantage of this feature being the compactness and discretion of overall, resulting in a short duct with high audio performance, while allowing a gain in architectural volume.

According to another advantageous characteristic, the assembly also comprises a protective grid covering the outlet of the duct, which makes it possible to protect the duct against the entry of any undesirable elements such as rodents in particular. According to another advantageous characteristic, the outer periphery of the second end is configured so as to form a bearing surface in the exit plane in the form of a flange, which makes it possible to fix the assembly to the body of the vehicle of the side of the duct outlet.

According to an advantageous characteristic, said assembly is in one piece, in particular molded, preferably in plastic, which makes it possible to have a single part that can be mounted on the vehicle, avoiding a system that can be mounted in several parts which is difficult to seal, which therefore generates both time saving during assembly and better sealing.

The invention also relates to an audio system comprising an assembly according to the invention and a loudspeaker housed in the box, the loudspeaker closing off said opening in the first face of the box, the first end of the duct opening onto the internal volume of the box. box located at the rear of the speaker. This system has similar advantages to those of the assembly by including the loudspeaker, the associated advantage is that the assembly is vehicle mountable in one go, the loudspeaker being pre-assembled on the assembly.

The invention also relates to a motor vehicle comprising an audio system according to the invention, the second end of the duct forming the air outlet opening to the outside of the vehicle, which makes it possible to have a vehicle incorporating a compact volume. audio system, while promoting acoustic audio delivery.

According to an advantageous characteristic, said audio system is attached to a quarter panel lining, which allows perfect integration into the sheet metal work and without penalizing either the volume of the vehicle trunk, or the structural performance of the sheet metal body, to which the vehicle belongs. quarter panel lining which corresponds to the rear part of a wing, in particular the characteristics of stiffness, vibration or its behavior in passive safety.

According to an advantageous characteristic, the box is located in a chapel

shock absorber attached to the quarter panel lining, which allows a gain in architectural volume and great discretion in the audio system.

According to another advantageous characteristic, the second end of the duct is located in a wheel arch of the quarter panel lining, which makes it possible to be invisible from the outside and thus protected against certain hazards.

According to another advantageous characteristic, a reinforcement, preferably rear, of the damper cap has a narrowed depth freeing a volume suitable for housing said duct. This feature allows easy assembly of the system, in particular in a movement of one hand. In addition, as this characteristic makes it possible not to require a removable duct, this improves the rigidity of the box, as well as the geometry-tightness-reliability triptych. In fact, the use of a variable-geometry duct instead of a removable duct makes it possible to shorten the duct to optimize the section / length ratio and thus optimize the architectural volume and the acoustic performance.

According to another advantageous characteristic, the vehicle comprises a polyurethane seal compressed at 50% between the flange of the duct and an associated bearing surface of the wheel arch of the rear quarter panel of the vehicle, which completes the sealing of the audio system.

Other advantages and characteristics of the invention will become apparent on reading the description and the figures illustrating in particular a preferred embodiment.

Figure 1 shows a perspective view of the assembly according to the invention; and,

Figure 2 shows a duct side view of the assembly according to the invention; and,

Figure 3 shows a view of a first half-shell of the assembly according to the invention; and,

Figure 3 shows a view of the second half-shell of the assembly according to the invention; and,

Figure 5 shows a perspective view of the audio system according to the invention; and,

Figure 6 shows a sectional view in the YZ plane of the audio system at the entrance to the duct, according to a preferred embodiment of the invention; and,

Figure 7 shows a view of the fender liner and trunk of a vehicle according to the invention; and,

Figure 8 shows a view in the XZ plane of the system as installed

preferably in the quarter panel lining of a vehicle according to the invention; and,

Figure 9 shows a sectional view in the XY plane of the system in a vehicle according to the invention; and,

Figure 10 shows a view of the rear left wing at the level of the wheel arch, on the outside of the vehicle according to the invention, showing the air outlet grille; and,

FIG. 11 represents a view of the shock absorber chapel and of its reinforcements in a vehicle according to the invention. Throughout the text, the directions and orientations are designated with reference to a direct orthonormal reference XYZ conventionally used in automotive design, in which X designates the longitudinal direction of the vehicle, directed towards the front of the vehicle, Y is the direction transverse to the vehicle, directed to the left and Z is the vertical direction directed upwards. The concepts “front” and “rear” are indicated with reference to the normal direction of travel towards the front of the vehicle. Throughout the description, the term “substantially” means that a slight deviation can be allowed with respect to a determined nominal position or orientation, for example “substantially perpendicular” means that a deviation of the order of 20 ° per in relation to a strictly perpendicular orientation is allowed within the framework of the invention. For greater clarity, identical or similar elements are identified by identical reference signs in all of the figures.

According to a preferred embodiment of the invention shown in Figure 1, there is shown a perspective view of an assembly 1 for a motor vehicle, placed on the face opposite to the face intended to accommodate the loudspeaker. Set 1 comprising:

a box 2, of substantially cylindrical shape here, with two flat faces and a curved face, forming an internal volume, in particular configured to house a loudspeaker, the first flat face of the box 2 comprising an opening 3 capable of receiving a high - speaker, and the curved face of the box comprising an orifice 4 configured to receive a duct and the orifice 4 being in a plane perpendicular to the first face of the box 2,

a conduit 5 for a subwoofer comprising a main portion delimited by a first and a second open ends, the first end being connected to the box 2 and the opening of which corresponds to said orifice 4 forming an inlet and the second end being open and configured to open out towards the outside of the vehicle forming an outlet, said assembly being characterized in that the main portion of the duct has a passage section whose geometry, but not the area, varies between its two ends, the first end of the duct having a different geometric shape from the second end of the duct 5. In particular, the figure shows a triangular shape of the inlet section, that is to say of the orifice 4 of the duct 5 and an ovoid shape, that is to say elliptical, of the outlet section 6 of the duct 5. It can also be seen that the second end is protected by a protective grid which forms part of the single piece formed by assembly 1 (box 2 and duct 5). The outer periphery of the second end of the duct 5 is also configured so as to form a bearing surface in the exit plane in the form of a flange 6b, here flat. This flange 6b has two holes suitable for receiving the two centering studs 105 (not shown here) located in the wheel arch of the fender liner of the vehicle body once the assembly 1 is mounted on the vehicle. The flange 6b is fixed to the wheel arch by means of one screw per centering pin 105, this embodiment not being limiting, more studs can be provided depending on the space available. As shown here, in a preferred embodiment, a collar 6c, made from the same material and forming an integral part of the one-piece assembly 1, extends the duct 5 beyond the flange 6b over a few millimeters in length, preferably 7 mm, with a thickness of about 1 mm so as to constitute a centering means during mounting on the vehicle and also so as to form a baffle as the first sealing wall once the assembly 1 has been mounted on the vehicle. Advantageously, this collar 6c comprises chamfered slots to facilitate the assembly of the assembly 1 on the vehicle. On the flange 6b is glued an annular polyurethane gasket 6d, this gasket 6d, which is therefore not part of the one-piece assembly, is glued to the assembly before mounting on the vehicle and makes it possible to make a second seal around the outlet of air. The seal 6d is positioned around the flange 6c and its thickness, preferably 4 mm, is less than the height of the flange 6c (excluding slots, preferably 2 mm high).

In Figure 2 is shown a side view of the conduit 5 of the assembly 1 with the orientation representative of that which it would have in the vehicle according to a view in the YZ plane. In this preferred embodiment, the duct 5 extends along an axis inclined at least by at least 20 °, relative to the plane formed by the first face of the box. An angle value of approximately 25 ° is preferably chosen for reasons of architectural optimization, which corresponds, once mounted on the vehicle, to an inclination of approximately 25 ° with respect to the vertical, this orientation allows optimization inserting assembly 1 into the shock absorber chapel, without having to reassemble the Z-shaped seat belt retractor, and respecting the operating clearance with the rear shock absorber, which also makes it possible not to encroach on the boot space. In fact, with this inclination, the architectural volume of the duct is located in the extension along the X axis of the architectural volume of the box, and does not protrude from the Y-shaped influence of the box. Indeed, the duct cannot be placed in the center of the rear volume of the box, behind the loudspeaker, because this would then require making a passage of duct in the reinforcement of the damper chapel which houses the box, which it is preferable to avoid since such a duct would be at least in two parts in order to be mountable on the vehicle, which would imply difficulties in achieving its seal, whereas this is essential on such a part connecting the exterior of the vehicle to the passenger compartment through the loudspeaker (via the loudspeaker membrane on the one hand and via the protective grille on the other). The orientation of the angle of 25 ° is towards the outside of the vehicle since the assembly is attached, that is to say fixed directly, to the quarter panel lining, in the left fender of the vehicle. If the assembly had been attached to the quarter panel lining in the right fender of the vehicle, the orientation of 25 ° would have been in the other direction so that the exit opens out to the outside of the vehicle. 5. Finally, the shape of the duct comes from the fact that the duct is designed so that the area of the passage section remains constant along the main section between the inlet and the outlet, while the inlet is triangular and the outlet ovoid, hence the evolutionary geometry of this conduit. There is also the flat flange 6b in the outlet plane 6 of the duct 5 as well as the collar 6c.

In a preferred embodiment the assembly is molded to then form a single piece. The plastic injection molding process being preferred given its simplicity, speed and robustness, making it possible to limit dispersions. For this, two half-shell molds are used, the two half-shells are then obtained by molding and then welded and / or glued to obtain the assembly 1, which makes it possible to overcome sealing problems. Of course, the use of a single mold to directly obtain the assembly 1 is also possible with a more sophisticated molding process, or by other manufacturing process, such as three-dimensional printing for example. In FIG. 3 is shown a view of a first half-shell of the assembly 1. The assembly formed of the two half-shells then forms a single piece of plastic material. A hard plastic is preferred to avoid deformation and ensure good aging. The half-shells are not symmetrical, this first half-shell is the most voluminous, the second corresponds to its cover, which is almost flat. This first half-shell comprises the volume delimited by the rear of the loudspeaker, part of the volume of the duct and the second end of the duct, that is to say the outlet 6 of the duct, of ovoid shape, covered and closed by a grid protecting the outlet 6 of the duct 5. This figure also shows the shape of the duct and in particular that its inlet 4 extends in an inlet plane substantially perpendicular to the outlet plane in which the outlet extends. 6 of the duct 5. There is also the flat flange 6b in the outlet plane 6 of the duct 5 comprising the protective grid which closes the second end of the duct 5. It can also be seen in this figure that the outer contour of the main portion of the duct 5. conduit 5 has the shape of a quarter disc in the plane perpendicular to the inlet plane 4 or to the outlet plane 6. The length of the conduit is measured on the neutral fiber, shown in dotted lines in the figure. The neutral fiber is the curve which connects to each other all the centers of the passage sections of the duct 5 between the entry plane 4 and the exit plane 6. The neutral fiber takes almost the shape of a quarter of a circle. , and its length is approximately 1 12 mm, which is short, so as to guarantee good acoustic performance. This short duct 5 could be obtained thanks to this rounded shape in a quarter of a circle. The figure also shows a power cable and part of its connector 7a which will be connected to the speaker of the audio system to supply it and which are added after the molding on this half-shell of the assembly. In Figure 4 is shown the second half-shell of the assembly 1 which serves as a cover for the first half-shell. The face shown is the internal face of the half-shell, that is to say the face which will be in contact with the loudspeaker to press it down, it is therefore also the inside of the duct 5 which is visible on the figure. The three holes 8 in the first face of the box 2 are part of the means for fixing to the box. Indeed, these three holes 8 will receive fixing screws to the shock absorber chapel of the vehicle. The four holes 9a are those which will be used to receive the screws 9b (not shown in this figure) for fixing the loudspeaker on the assembly 1, and between the two parts will be inserted a silicone gasket (not visible here) so to form a seal.

In Figure 5 is shown a perspective view of the audio system 10 comprising the assembly 1 and a speaker 11 housed in the box 2, the speaker 1 1 closing off the opening 3 in the first face of the box. The volume of the assembly 1 being closed once the loudspeaker 11 is included in the assembly 1 to form the audio system 10, the two openings 3 and 6 on the outside being closed on one side by the loudspeaker 11 and on the other side by the grille protecting the outlet 6 of duct 5. The overall volume is thus compact, the greatest depth P (along the Y axis) is located at the level of the box 2 and measures approximately 120 mm , the greatest height H (along the Z axis) is also located at this location to accommodate the loudspeaker 1 1 and measures approximately 250 mm and the length L (along the X axis) extends between the outlet 6 of the duct and the end of the box and measures approximately 325 mm. The closure between the loudspeaker 11 and the assembly 1 is made by means of four screws 9b which are screwed into the holes 9a provided in the assembly 1 and which enclose a silicone seal. The figure also shows the flange 6b and the power cable fixed on one side to the loudspeaker by part of its connector 7a and on the other side to an electrical inlet by means of the other part of its connector. 7b visible here.

FIG. 6 represents a sectional view in the YZ plane of the audio system 10 at the level of the plane of the inlet 4 of the duct, it can be clearly seen that the orifice 4 forming the entrance of the first end of the duct has a triangular shape . The volume of duct 5 is not used as a subwoofer since a known and applied principle is to use the vehicle interior as a subwoofer, duct 5 constituting a vent connected to the outside of the vehicle for propagate the waves, the passenger compartment and the exterior being isolated and sealed via the loudspeaker 1 1. The area of the passage section of the duct 5 remains constant between the outlet 6 and the inlet 4 of the duct, here 4 cm ² approximately, in fact the base of the triangle is here approximately 122 mm and its height approximately 46 mm. The choice of this area is linked to the length of the duct so as to allow optimal acoustic qualities. The audio system 10 is here shown on the vehicle, on this section we therefore also see the reinforcement 101a of the rear shock absorber chapel which has a narrowed depth freeing a volume capable of accommodating the duct 5, and more specifically capable of accommodating the passage section corresponding to the inlet 4, here triangular, of the duct 5. It is in particular thanks to this integration, the duct 5 does not have to be removable and can be assembled as a single piece, which saves time on the assembly process and limits the number of parts to be managed and assembled in the factory.

Figure 7 shows a view of the rear left interior of a vehicle 100 including an audio system 10 according to the invention. The audio system 10 is more precisely attached to the quarter panel lining 102 of the vehicle 100. For greater visibility, the trunk side trim is not present in the figure in order to view the audio system 10. In fact, on a vehicle the Lateral trunk trim covers the entire area up to the shelf and the shelf support making the audio system 10 invisible, in particular the duct 5. In fact, the only visible part seen from the trunk is an aesthetic grille which covers the loudspeaker January 1 not shown here, this aesthetic grid being fixed to a frame which also maintains the side trunk trim.

FIG. 8 represents a view in the XZ plane of the audio system as preferably installed in the quarter panel lining 102 of the vehicle 100. The casing 2 of the assembly 1 of the audio system 10 is located in the rear shock absorber chapel, formed by the shock absorber chapel reinforcements 101a, 101b and the shelf support 104, above the left rear shock absorber head 103, in the left wing of the vehicle body 100. The first end of the duct 5 opening onto the internal volume of the subwoofer 2 located at the rear of the loudspeaker 1 1, the second end of the duct 5 opening onto an air outlet outside the vehicle 100, more precisely the second end of the duct is located in the rear wheel arch of the rear quarter panel liner 102 of the vehicle body 100. The audio system 10 is attached to the vehicle body by means of five fasteners 8 (one is not visible here ) comprising three screws inserted in three fixing holes 8 located on the first face of the box 2 and by means of two holes 8 (one is not visible) intended to receive two centering studs on the flange 6b of the duct 5 at the level of the exit plane 6 of the duct 5. We also distinguishes in this figure four slots 106 intended to receive means for fixing the frame provided on the one hand to carry the aesthetic grille of the speaker 11 and on the other hand to rigidly maintain the side trunk trim (not shown here) . In order to guarantee the tightness of the audio system 10, a principle of main isostatism of the box giving priority to the tightness of the duct 5 / wheel arch, unlike a standard isostatism where it is the loudspeaker which has priority for the setting in geometry with the environment (cladding, fittings, sheet metal ...) is defined. In addition, this isostatism incorporates the constraints of the sheet metal environment: in terms of available volume, physical limits (vibrations, deformations of the damper chapel, etc.) and geometric constraints (dispersions, etc.). The defined isostatism therefore prioritizes the geometry of the box duct with respect to the sheet metal wheel arch of the vehicle 100, this in order to ensure the total tightness of the vehicle (no intrusion of water, dust, animals , road noise, etc ...). For this, the centering means by the collar 6c, making it possible to form a baffle as the first sealing wall, was installed. Then to complete the sealing function, the polyurethane gasket 6d, in particular in the form of foam, is compressed to 50% between the flange 6b of the duct 5 and an associated bearing surface of the vehicle consisting of the wheel arch in the quarter panel lining 102 Two screws 8 (only one of these two screws is visible in the figure) secure the flange 6b on the sheet metal bearing surface of the wheel arch, these two screws 8 being screwed in first in the assembly process. factory to ensure a perfect seal. The associated assembly kinematics therefore involves positioning the audio system 10 via the flange 6b in the centering studs 105, lowering the audio system 10 in Z to center it via its collar 6c, then pivoting the audio system around the axis Z until the supporting surface of the box 2 is placed in secondary ZX at the level of the loudspeaker 1 1 and screw the first two screws 8 ensuring the tightening of the flange 6b, the box 2 being inserted in the chapel d 'damper. The XY centering and the Z plane support are therefore carried out on the flange 6b, and the secondary positioning Y is carried out on the extreme front high fixing of the box, so as to ensure its plating on the shock absorber cap, and its correct screwing. via the remaining three screws 8. This isostatism ensures the main sealing function, and allows the design of a one-piece duct casing. The assembly of the audio system 10 in one piece is thereby simplified and less expensive. This audio system and this assembly can thus be adapted to any audio application in areas constrained in terms of architectural volume with a closed passenger compartment (public transport, boating, agriculture, etc.).

Figure 9 shows a sectional view in the XY plane of the system 10 in a vehicle. The cut is made at mid-height of the loudspeaker and makes it possible to distinguish the exit plane 6 of the duct 5 and in particular the elliptical, ovoid shape of the second open end of the duct 5. We can see in the flange 6b located in the plane outlet 6 of the duct 5 the two holes 8 suitable for receiving the two centering studs 105 for fixing the audio system 10 to the quarter panel lining 102.

FIG. 10 represents a view of the rear left wing at the level of the wheel arch, on the exterior side of the vehicle 100, and shows the protective grille of the air outlet 6 molded in plastic from the assembly 1. L ' area of the passage section remaining constant between the outlet 6 and the inlet 4 of the duct, the area of the ovoid is here also about 4 cm ² , this corresponds here to a first ellipse diameter of about 60 mm and to a second ellipse diameter of about 88 mm.

Figure 11 shows a view of the shock absorber chapel and its reinforcements in a vehicle 100 in which the audio system has not been shown for a better understanding. We can clearly see the rear shock absorber chapel, formed by the shock absorber chapel reinforcements 101 a, 101 b and the shelf support 104, above the left rear shock absorber head 103, in the left wing of the body of the vehicle 100. The rear reinforcement 101a of the left rear shock absorber chapel which has a narrowed depth freeing a volume capable of housing the duct is thus easily visible. Indeed, the rear reinforcement 101a of the rear left shock absorber chapel is narrowed at its base, that is to say that its shallowest depth is located at its base and then this depth increases continuously. Here, the depth reached at his head is the same as the single depth of reinforcement 101b front of the left rear shock absorber chapel. The passage formed by the absence of material is thus triangular so as to allow the duct which has a triangular passage section to pass near the inlet, while leaving a minimum clearance, for example of 3 mm, between the duct 5 and the reinforcement 101a at the rear of the damper chapel so as not to weaken the sheet metal or encroach on the trunk, and whose feasibility is validated by rib chain. This figure also clearly shows the mounting studs on the sheet metal bearing surface of the wheel arch in the quarter panel lining 102.

In general, it will be understood that the fact that the passage section remains constant along the main section between the inlet and the outlet of the duct 5, means that it does not vary or not significantly, less of 10% for example.

Claims

1. Set (1) for motor vehicle (100) comprising:

- a box (2) forming an internal volume, in particular configured to house a loudspeaker (11), a first face of the box comprising an opening (3) suitable for receiving a loudspeaker (11), and a second face of the box comprising an orifice (4) configured to receive a duct (5), and

- a conduit (5) for a subwoofer comprising a main portion delimited by a first and a second open ends, the first end being connected to the box (5) and the opening of which corresponds to said orifice (4) forming an inlet, the second end being configured to open out towards the outside of the vehicle (100) forming an outlet (6), said assembly (1) being characterized in that the main portion of the duct (5) has a passage section whose geometry varies between its two ends, the first end of the duct having a different geometric shape from the second end of the duct (5).

2. Assembly (1) according to the preceding claim characterized in that the second face of the box is substantially perpendicular to the first face.

3. Assembly (1) according to any one of the preceding claims, characterized in that the duct (5) extends along an inclined axis, at least 20 °, relative to the plane formed by the first face of the box (2).

4. An assembly (1) according to any one of the preceding claims characterized in that the inlet (4) extends in an inlet plane substantially perpendicular to an outlet plane in which the outlet (6) extends. .

5. An assembly (1) according to any one of the preceding claims characterized in that the orifice (4) forming the inlet of the first end of the duct (5) has a triangular shape and / or in that the outlet ( 6) formed by the second open end of the duct (5) has an ovoid shape.

6. Assembly (1) according to any one of the preceding claims, characterized in that the area of the passage section remains constant along the main section between the inlet and the outlet of the duct (5).

7. An assembly (1) according to claim 4 characterized in that the outer contour of the main portion of the duct (5) has the shape of a quarter disc in the plane.

perpendicular to the entry plane or to the exit plane.

8. An assembly (1) according to any one of claims 4 to 7 characterized in that it also comprises in the exit plane a protective grid covering the outlet (6) of the duct (5).

9. An assembly (1) according to any one of claims 4 to 8 characterized in that the outer periphery of the second end (6) is configured so as to form a bearing surface in the exit plane in the form of 'a flange (6b).

10. Assembly (1) according to any one of the preceding claims, characterized in that said assembly is in one piece, in particular molded, preferably plastic.

11. Audio system (10) comprising an assembly (1) according to any one of the preceding claims and a loudspeaker (11) housed in the box (2), the loudspeaker (11) closing off said opening (3). in the first face of the box (2), the first (4) end of the duct opening onto the internal volume of the box (2) located at the rear of the loudspeaker (11).

12. Motor vehicle 100 characterized in that it comprises an audio system (10) according to the preceding claim, the second end of the duct (5) forming the outlet (6) of air opening to the outside of the vehicle (100). .

13. Motor vehicle (100) according to the preceding claim characterized in that said audio system (10) is attached to a quarter panel lining (102).

14. Motor vehicle (100) according to the preceding claim, characterized in that the box (2) is located in a damper chapel attached to the quarter panel lining (102).

15. Motor vehicle (100) according to any one of claims 13 to 14, characterized in that the second end (6) of the duct (5) is located in a wheel arch of the quarter panel lining (102).

16. Motor vehicle (100) according to any one of claims 14 to 15, characterized in that a reinforcement (101a), preferably rear, of the shock absorber chapel has a narrowed depth releasing a volume capable of accommodating said. conduit (5).

17. Motor vehicle (100) according to any one of claims 12 to 16, characterized in that it comprises a seal (6d) polyurethane compressed to 50% between the flange (6b) of the duct (5) and a surface d 'associated support of the wheel arch of the quarter panel lining (102) of the vehicle (100).