Motor vehicle inner trim panel

Abstract

The invention relates to a motor vehicle inner trim panel (1) comprising: a compressible cellular core (3), the core having a front face (4) and a reverse face (5), the core having open cells (6) opening on either side towards these faces; two plies, front (7) and reverse (8), for reinforcing the core, which plies are embedded in polyurethane foam; at least one electrodynamic transducer (10) secured on the side of the reverse ply, the transducer being secured in a stamped part (11) formed in the reverse ply, the foam filling the cells of the core opposite the stamped part, so as to connect the plies by a foam bridge (9).

Description

[0001] DESCRIPTION

[0002] Title: Interior trim panel of a motor vehicle

[0003] The invention relates to an interior trim panel for a motor vehicle and a method for producing such a panel.

[0004] It is known to produce an interior trim panel for a motor vehicle, said panel comprising a body, said body comprising:

[0005] • a compressible cellular core, said core having a front face and a back face, said core having open cells opening on either side towards said faces,

[0006] • two front and back plies reinforcing said core, said plies being based on entangled reinforcing fibers, said plies being embedded in polyurethane foam, said plies extending respectively on said front and back faces, said foam overmolding said core so as to associate said plies with said core, said panel further comprising at least one electrodynamic transducer fixed on the side of said back ply.

[0007] Such an arrangement makes it possible to produce a laminated panel with good rigidity provided by a “beam effect” produced by the reinforcing layers associated with each other via the core forming a means of spacing.

[0008] Such a panel is, for example, a luggage compartment cover shelf or a passenger compartment false floor.

[0009] The transducer is intended to emit a sound signal, for example from a radio or a record player, or of the "anti-noise" type so as to emit a sound in phase opposition with the noise generated inside the passenger compartment. A transducer has, compared to a loudspeaker, the advantages of occupying a small space and having a minimized mass.

[0010] As a reminder, transduction is the operation allowing one physical quantity to be transformed into another, using a transducer which transforms the energy received in a given form, for example electrical energy, into usable energy in a different form, for example acoustic.

[0011] In the context of the invention, it is a question of transforming an electrical signal into an acoustic signal by using as a radiation surface the support on which the transducer is fixed, in this case the body of the panel.

[0012] We recall here that a transducer differs from a loudspeaker in the following way:

[0013] • a loudspeaker comprises a magnet fixedly mounted on a support and a flexible membrane secured to a coil, said membrane vibrating when said loudspeaker is powered,

[0014] • a transducer comprises a coil fixedly mounted on a rigid plate and a magnet fixed on a block mounted by means of a suspension means on said coil, so that said plate vibrates when said transducer is powered.

[0015] Ultimately, a loudspeaker is a self-contained system generating sound independently of the environment in which it is mounted, whereas a transducer uses the support on which it is attached to generate the expected sound.

[0016] However, it is observed that fixing a transducer on a laminated panel body as described above does not allow optimal sound to be obtained, this being due to the thickness and the mass in relation to the transducer, in particular for high frequencies.

[0017] The object of the invention is to propose an arrangement making it possible to overcome this drawback. To this end, and according to a first aspect, the invention proposes an interior trim panel for a motor vehicle, said panel comprising a body, said body comprising:

[0018] • a compressible cellular core, said core having a front face and a back face, said core having open cells opening on either side towards said faces,

[0019] • two face and back plies reinforcing said core, said plies being based on entangled reinforcing fibers, said plies being embedded in polyurethane foam, said plies extending respectively on said face and back faces, said foam overmolding said core so as to associate said plies with said core, said panel further comprising at least one electrodynamic transducer fixed on the side of said back ply, said panel further having the following characteristics:

[0020] • said transducer is fixed in a stamping made in said backing sheet to form a housing for receiving said transducer, said stamping producing localized compression of said core so as to locally bring said sheets closer to each other,

[0021] • said foam fills said cells of said core opposite said stamping, so as to connect said layers by a foam bridge.

[0022] Such an arrangement makes it possible to localize acoustic waves as the frequencies increase.

[0023] In particular, when two transducers are installed, an improved stereo effect is obtained.

[0024] It will further be noted that fixing the transducer in a stamping makes it possible to minimize, or even eliminate, its protrusion from the back surface of the body. According to a second aspect, the invention proposes a method for producing such a panel.

[0025] Other features and advantages of the invention will appear in the following description, given with reference to the attached figures, in which: [Fig.1] is a schematic view in partial section of a panel according to one embodiment.

[0026] [Fig.2] is an enlarged schematic detail view of Figure 1,

[0027] [Fig.3] is an enlarged schematic detail view of Figure 2 taken to schematically show the structure of an electrodynamic transducer as used in the invention.

[0028] With reference to the figures, a motor vehicle interior trim panel 1 is described, said panel comprising a body 2, said body comprising:

[0029] • a compressible cellular core 3, said core having a front face 4 and a back face 5, said core having open cells 6 opening on either side towards said faces,

[0030] • two front 7 and back 8 plies for reinforcing said core, said plies being based on entangled reinforcing fibers, said plies being embedded in polyurethane foam, said plies extending respectively on said front and back faces, said foam overmolding said core so as to associate said plies with said core, said panel further comprising at least one electrodynamic transducer 10 fixed on the side of said back ply, said panel further having the following characteristics:

[0031] • said transducer is fixed in a stamping 11 made in said backing sheet to form a housing for receiving said transducer, said stamping producing a localized compression of said core so as to locally bring said sheets closer to each other,

[0032] • said foam fills said cells of said core opposite said stamped part, so as to connect said layers by a foam bridge 9. According to the embodiment shown, the core 3 is formed by a honeycomb structure whose cells open towards the front 4 and back 5 faces, said core having intercellular walls 12 crushed opposite the stamped part 11.

[0033] Depending on the various designs, the honeycomb is made from cardboard, thermoplastic material, or even aluminum.

[0034] According to various embodiments, the stamped part 11 has a surface area of ​​between 50 and 600 cm 2 .

[0035] According to various embodiments, the stamped part 11 has a generally circular or rectangular shape.

[0036] Depending on the various applications, the reinforcing fibers are glass fibers or natural fibers (flax, cotton, hemp, etc.).

[0037] According to various achievements not shown:

[0038] • either the body 2 further comprises a backing coating layer - for example in the form of non-woven fabric -, the transducer 10 being fixed to said layer,

[0039] • either said body is devoid of a backing coating layer, said transducer being fixed to the backing reinforcement sheet 8.

[0040] According to various embodiments, the backing layer of the covering is glued or overmolded by the foam of the reinforcing backing sheet 8.

[0041] According to an embodiment not shown, the panel 1 further comprises a face covering layer, for example carpet.

[0042] According to various embodiments, the front covering layer is glued or overmolded by the foam of the front reinforcement ply 7. According to various embodiments not shown, the transducer 10 is fixed:

[0043] • with glue,

[0044] • and / or by rivets,

[0045] • and / or by screws,

[0046] • and / or by fitting into a plate secured to the body 2.

[0047] According to one embodiment, the reinforcing fibers are bonded together by a bonding agent, for example in the form of resin.

[0048] According to the embodiment shown, the stamped part 11 is provided in its central part with an excess thickness forming a stud 15 - for example cylindrical -, the transducer 10 comprising a coil 16 and a magnet 17 fixed on a block 18 mounted in suspension relative to said coil by a suspension means 19, said coil being fixed on said stud and said stud being dimensioned so that said block is spaced from the body 2 by a clearance allowing it to vibrate without interference with said body, in order to avoid the appearance of parasitic noise.

[0049] According to one embodiment, the stud 15 has a height of less than 3 mm,

[0050] According to one embodiment, the reinforcing plies 7,8 have a surface mass of between 200 and 500 g / m 2 .

[0051] A method of manufacturing a panel 1 is now described, in a manner not shown, said method comprising the following steps:

[0052] • provide a compressible cellular core 3, said core having a front face 4 and a back face 5, said core having open cells 6 opening on either side towards said faces,

[0053] • placing two reinforcement layers of front 7 and back 8 on each of said faces, said layers being based on entangled reinforcement fibers, • pouring onto each of said layers a precursor mixture of polyurethane foam,

[0054] • placing the assembly in a mold defining a molding cavity, said mold being provided with a boss projecting into said cavity so as to locally crush said core to form a stamping 11 on the side of said backing sheet,

[0055] • waiting for the foam to expand so as to form front 7 and back 8 reinforcement plies impregnated with foam, said foam overmolding said core, so as to associate said plies with said faces, said foam filling said core opposite said stamping,

[0056] • remove the assembly from said mold and fix a transducer 10 in said stamping.

[0057] In order to ensure good filling of the core 3 with the foam opposite the stamped part 11, it may be provided to have an excess of foam precursor mixture opposite the area intended to form said stamped part.

[0058] It is also possible to provide for associating at least one layer of face and / or back of covering on at least one layer of reinforcement 7,8, in particular by gluing or by overmolding with the foam in the mold.

Claims

CLAIMS 1. Interior trim panel (1) of a motor vehicle, said panel comprising a body (2), said body comprising: • a compressible cellular core (3), said core having a front face (4) and a back face (5), said core having open cells (6) opening on either side towards said faces, • two face (7) and back (8) plies for reinforcing said core, said plies being based on entangled reinforcing fibers, said plies being embedded in polyurethane foam, said plies extending respectively on said face and back faces, said foam overmolding said core so as to associate said plies with said core, said panel further comprising at least one electrodynamic transducer (10) fixed on the side of said back ply, said panel being characterized in that: • said transducer is fixed in a stamped part (11) made in said backing sheet to form a housing for receiving said transducer, said stamped part carrying out a localized compression of said core so as to locally bring said sheets closer to each other, • said foam fills said cells of said core opposite said stamping, so as to connect said layers by a foam bridge (9).

2. Panel according to claim 1, characterized in that the core (3) is formed by a honeycomb structure whose cells (6) open towards the front (7) and back (8) faces, said core having intercellular walls (12) crushed opposite the stamping (11).

3. Panel according to the preceding claim, characterized in that the honeycomb is based on cardboard, thermoplastic material or aluminum.

4. Panel according to any one of the preceding claims, characterized in that the stamped part (11) has a surface area of ​​between 50 and 600 cm 2 .

5. Panel according to any one of the preceding claims, characterized in that: • either the body (2) further comprises a backing coating layer, the transducer (10) being fixed on said layer, • either said body is devoid of a backing coating layer, said transducer being fixed to the backing reinforcement sheet (8).

6. Panel according to any one of the preceding claims, characterized in that the transducer (10) is fixed: • with glue, • and / or by rivets, • and / or by screws, • and / or by fitting into a plate attached to the body (2).

7. Panel according to any one of the preceding claims, characterized in that the stamped part (11) is provided in its central part with an excess thickness forming a stud (15), the transducer (10) comprising a coil (16) and a magnet (17) fixed on a block (18) mounted in suspension relative to said coil by a suspension means (19), said coil being fixed on said stud and said stud being dimensioned so that said block is spaced from the body (2) by a clearance allowing it to vibrate without interference with said body.

8. Method of manufacturing a panel (1) according to any one of the preceding claims, characterized in that it comprises the following steps: • provide a compressible cellular core (3), said core having a front face (4) and a back face (5), said core having open cells (6) opening on either side towards said faces, • arrange two face (7) and back (8) reinforcement plies on each of said faces, said plies being based on entangled reinforcement fibers, • pour onto each of said layers a precursor mixture of polyurethane foam, • placing the assembly in a mold defining a molding cavity, said mold being provided with a boss projecting into said cavity so as to locally crush said core to form a stamping (11) on the side of said backing sheet, • waiting for the foam to expand so as to form face (7) and back (8) reinforcement layers impregnated with foam, said foam overmolding said core, so as to associate said layers with said faces, said foam filling said core opposite said stamping, • remove the assembly from said mold and fix a transducer (10) in said stamping.

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