Architecture for mounting an inertial electrodynamic transducer in an interior compartment of a motor vehicle

Abstract

The invention relates to an architecture (1) for mounting an inertial electrodynamic transducer (2) in an interior compartment of a motor vehicle, said architecture comprising a box (3) having an opening (4), a rigid plate (5) fixed by its periphery to the periphery of said opening by means of a decoupling means (6), at least one transducer (2) integral with a rigid plate (12) fixedly mounted on said plate, said plate is provided with an orifice (16) allowing passage of said box in an axial direction, said plate rests in adjusted contact by a peripheral strip (17a) on a reciprocal peripheral strip (17b) extending around said orifice on said external face, it further comprises a means for fixing said plate on said plate.

Description

[0001] The invention relates to a mounting architecture for an inertial electrodynamic transducer in an interior compartment of a motor vehicle.

[0002] It is known to create a mounting architecture for an inertial electrodynamic transducer within an interior compartment of a motor vehicle, said architecture comprising: a rigid box defining an acoustic volume, said box having an opening, a rigid plate fixed by its periphery to the periphery of said opening by means of a decoupling means allowing its movement relative to said box so as to enable it to vibrate, said plate having an inner face turned towards said acoustic volume and an opposite outer face, at least one inertial electrodynamic transducer intended to enable said plate to vibrate, said transducer comprising a coil, provided with an axis of symmetry, one axial end of which is integral with a rigid plate, said plate being fixedly mounted on said plate, said transducer further comprising a magnet housed in a casing, said casing being mounted by means of a suspension means on said coil, so that said plate vibrates when said transducer is powered.

[0003] As a reminder, transduction is the operation that transforms one physical quantity into another, using a transducer that transforms the energy received in a given form, for example electrical energy, into usable energy in a different form.

[0004] Within the framework of the invention, it is a question of transforming an electrical signal into an acoustic signal by using as a radiating surface the rigid plate on which the transducer is fixed, for example in order to deliver a sound audible to an occupant of the seat (music, message, ...) or a sound signal in opposite phase with the sound signal corresponding to the noise in the passenger compartment when the vehicle is in motion.

[0005] It is worth recalling here that a transducer differs from a loudspeaker in the following way: a loudspeaker comprises a magnet fixedly mounted on a support and a flexible diaphragm attached to a coil, said diaphragm vibrating when said loudspeaker is powered; a transducer comprises a coil fixedly mounted on a rigid plate and a magnet mounted by means of a suspension means on said coil, so that said plate vibrates when said transducer is powered.

[0006] Ultimately, a loudspeaker is a self-contained system that generates sound independently of the environment in which it is mounted, whereas a transducer uses the support on which it is fixed, in this case a rigid plate, to generate the expected sound.

[0007] Furthermore, the use of a transducer is advantageous because it is smaller and lighter than a loudspeaker.

[0008] According to the known embodiment, the transducer plate is mounted overlapping the inner face of the plate.

[0009] However, in the case where the vehicle has a limited space along an axial direction, it may be impossible to accommodate the aforementioned architecture.

[0010] The invention aims to provide an architecture with reduced axial dimensions to allow it to be housed in a small space along the axial direction, while preserving the quality of sound emission.

[0011] To this end, the invention proposes a mounting architecture for an inertial electrodynamic transducer in an interior compartment of a motor vehicle, said architecture comprising: a rigid box defining an acoustic volume, said box having an opening, a rigid plate fixed by its periphery to the periphery of said opening by means of a decoupling means allowing its movement relative to said box so as to enable it to vibrate, said plate having an inner face turned towards said acoustic volume and an opposite outer face, at least one inertial electrodynamic transducer intended to enable said plate to vibrate, said transducer comprising a coil, provided with an axis of symmetry, one axial end of which is integral with a rigid plate, said plate being fixedly mounted on said plate, said transducer further comprising a magnet housed in a casing, said casing being mounted by means of a suspension means on said coil, so that said plate vibrates when said transducer is powered, said architecture also presents the following characteristics: said plate is provided with an orifice allowing the passage of said housing in an axial direction, said plate rests in contact adjusted by a peripheral band on a reciprocal peripheral band extending around said orifice on said external face, so as to achieve a seal between said bands, it further includes a means of fixing said plate to said plate.

[0012] In this description, the term "axial" is taken in reference to the axis of symmetry of the coil.

[0013] With the proposed arrangement, the plate is offset outwards, which reduces the axial dimension of the box by the thickness of the plate added to that of the plate.

[0014] This results in the possibility of reducing the plate thickness to the overall axial dimension of the architecture.

[0015] The result is that the architecture exhibits better compactness along the axial direction, which allows it to be housed in a space of reduced dimensions along said direction.

[0016] In practice, we can reduce the axial dimension of the architecture by 10 to 30% depending on the case.

[0017] In addition, the plaintiff unexpectedly observed that the plate with the insert exhibits a modal behavior analogous (evaluated by acoustic radiation, as will be seen later) to that of a prior art plate without an orifice, where said insert is mounted over the inner face of said plate.

[0018] Such an arrangement is applicable to all types of transducers, regardless of their size and the frequency bands involved.

[0019] Because of the space saved, the transducer can be installed in a multitude of locations in the vehicle: in a floor under a seat, a window pillar, a headrest, a luggage compartment, a roof, etc.

[0020] Other features and advantages of the invention will become apparent in the following description, made with reference to the accompanying figures, in which: [ Fig.1 ] is a general schematic view of an architecture according to the invention, [ Fig.2a ] And [ Fig.2b ] are schematic views of details of an architecture according to prior art ( figure 2a ) and according to the invention ( figure 2b ), [ Fig.3 ] represents measurement curves, carried out in a reference vehicle, of the sound pressure level (in dB) as a function of frequency (in Hz) for a reference architecture according to the prior art (solid line curve) and for an architecture according to the invention (dotted line curve).

[0021] With reference to the figures, an architecture 1 for mounting an inertial electrodynamic transducer 2 in an interior compartment of a motor vehicle is described, said architecture comprising: a rigid box 3 defining an acoustic volume, said box having an opening 4, a rigid plate 5 fixed by its periphery to the periphery of said opening by means of a decoupling means 6 allowing its movement relative to said box so as to enable it to vibrate, said plate having an inner face 7 facing said acoustic volume and an opposite outer face 8, at least one inertial electrodynamic transducer 2 intended to enable said plate to vibrate, said transducer comprising a coil 10, provided with an axis of symmetry 11, one axial end of which is integral with a rigid plate 12, said plate being fixedly mounted on said plate, said transducer further comprising a magnet 13 housed in a casing 14, said casing being mounted by means of a suspension means 15 on said coil,so that said plate vibrates when said transducer is powered, said architecture also presents the following characteristics: said plate is provided with an orifice 16 allowing the passage of said housing in an axial direction, said plate rests in adjusted contact by a peripheral band 17a on a reciprocal peripheral band 17b extending around said orifice on said external face, so as to achieve a seal between said bands, it further includes a means of fixing said plate, not shown.

[0022] Although not shown, it may be possible to provide box 3 with perforations allowing communication with the outside.

[0023] According to one embodiment, plate 5 has a Young's modulus between 10⁸ and 10⁹ Pa, plate 12 has a Young's modulus greater than or equal to that of said plate.

[0024] According to one design, plate 5 is made of rigid polyurethane foam reinforced with overmolded fiberglass.

[0025] Not shown, plate 5 may be provided with a rigid alveolar reinforcement structure embedded in the foam, said structure being in particular in the form of a honeycomb, being for example made of cardboard.

[0026] According to one design, plate 12 is made from injection-molded plastic material.

[0027] Not shown, in the case where the plate 12 is based on molded plastic material, the fastening means may include molded elements in one piece, said elements being shaped to snap into reciprocal elements provided on the plate 5.

[0028] According to various unshown designs, the fastening method may include screws, glue, welding, etc...

[0029] According to various embodiments, the decoupling means 6 is in the form of a rubber or elastically compressible foam seal.

[0030] According to one embodiment, the suspension means 15 is based on spring metal.

[0031] We now describe the curves represented in figure 3 .

[0032] It is observed that the acoustic radiation of the plate 5, measured between 20 and 16,000 Hz, is similar for an embodiment according to the invention (curve 2 in dotted line) and an analogous embodiment according to the prior art (curve 1 in solid line), this resulting, surprisingly, from an analogous modal behavior for a plate 5 without an orifice and a plate 5 having an orifice 16 filled by a rigid plate 12.

Claims

1. Architecture (1) for mounting an inertial electrodynamic transducer (2) in an interior compartment of a motor vehicle, said architecture comprising: • a rigid box (3) defining an acoustic volume, said box having an opening (4), • a rigid plate (5) fixed by its periphery to the periphery of said opening by means of a decoupling means (6) allowing its movement relative to said box so as to enable it to vibrate, said plate having an inner face (7) facing said acoustic volume and an opposite outer face (8), • at least one inertial electrodynamic transducer (2) intended to enable said plate to vibrate, said transducer comprising a coil (10), provided with an axis of symmetry (11), the axial end of which is integral with a rigid plate (12), said plate being fixedly mounted on said plate,said transducer further comprising a magnet (13) housed in a casing (14), said casing being mounted by means of a suspension means (15) on said coil, so that said plate vibrates when said transducer is powered, said architecture being , characterized in that • said plate is provided with an orifice (16) allowing the passage of said housing in an axial direction, • said plate rests in close contact by a peripheral band (17a) on a reciprocal peripheral band (17b) extending around said orifice on said external face, so as to achieve a seal between said bands, • it further includes a means of fixing said plate to said plate.

2. Architecture (1) according to claim 1, characterized in that plate (5) has a Young's modulus between 10 8 and 10 9 Pa, the plate (12) having a Young's modulus greater than or equal to that of said plate.

3. Architecture (1) according to any one of the preceding claims, characterized in that plate (5) is made of rigid polyurethane foam reinforced with overmolded fiberglass.

4. Architecture (1) according to any one of the preceding claims, characterized in that the plate (12) is made of injection-molded plastic material.

5. Architecture (1) according to any one of the preceding claims, characterized in that the decoupling means (6) is in the form of a rubber or elastically compressible foam seal.

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