Interior trim panel of a motor vehicle

Abstract

The invention relates to an interior trim panel (1) for a motor vehicle 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 both sides towards said faces; two layers, front (7) and back (8), reinforcing said core embedded in polyurethane foam; at least one electrodynamic transducer (10) fixed to the side of said back layer, said transducer being fixed in a recess (11) formed in said back layer, said foam filling said cells of said core opposite said recess, so as to connect said layers by a foam bridge (9). Figure 2

Description

Title of the invention: Interior trim panel for a motor vehicle

[0001] The invention relates to an interior trim panel for a motor vehicle and a method for producing such a panel.

[0002] It is known to produce an interior trim panel for a motor vehicle, said panel comprising a body, said body comprising: • 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, • 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,

[0003] said panel further comprising at least one electrodynamic transducer fixed on the side of said backing sheet.

[0004] Such an arrangement makes it possible to produce a laminated panel with good rigidity provided by a “beam effect” produced by the reinforcing plies associated with each other via the core forming a spacing means.

[0005] Such a panel is, for example, a luggage compartment cover shelf or a passenger compartment false floor.

[0006] The transducer is intended to emit a sound signal, for example from a radio or a disc player, or of the “anti-noise” type so as to emit a sound in phase opposition with the noise generated inside the passenger compartment.

[0007] A transducer has, compared to a loudspeaker, the advantages of taking up little space and having a minimized mass.

[0008] For the record, transduction is the operation enabling one physical quantity to be transformed into another, by means of 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.

[0009] 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.

[0010] We recall 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 membrane secured to a coil, said membrane vibrating when said loudspeaker is powered, • 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.

[0011] 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 fixed to generate the expected sound.

[0012] 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.

[0013] The aim of the invention is to propose an arrangement making it possible to overcome this drawback.

[0014] 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: • 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, • 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,

[0015] said panel further comprising at least one electrodynamic transducer fixed on the side of said backing sheet, said panel further having the following characteristics: • 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, • said foam fills said cells of said core opposite said stamping, so as to connect said layers by a foam bridge.

[0016] Such an arrangement makes it possible to localize the acoustic waves as the frequencies increase.

[0017] In particular, when two transducers are installed, a stereo effect is obtained. improved.

[0018] It will also 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.

[0019] According to a second aspect, the invention proposes a method for producing such a panel.

[0020] Other features and advantages of the invention will appear in the following description, given with reference to the attached figures, in which:

[0021] [Fig.l] is a schematic view in partial section of a panel according to one embodiment.

[0022] [Fig.2] is an enlarged schematic detail view of [Fig.l],

[0023] [Fig.3] is an enlarged schematic detail view of [Fig.2] taken to show schematically the structure of an electrodynamic transducer as used in the context of the invention.

[0024] With reference to the figures, a motor vehicle interior trim panel 1 is described, 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 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,

[0025] said panel further comprising at least one electrodynamic transducer 10 fixed on the side of said backing sheet, said panel further having the following characteristics: 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, said foam fills said cells of said core opposite said stamping, so as to connect said layers by a foam bridge 9.

[0026] 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.

[0027] According to various embodiments, the honeycomb is made from cardboard or thermoplastic material, or even aluminum.

[0028] According to various embodiments, the stamped part 11 has a surface area of ​​between 50 and 600 cm2.

[0029] According to various embodiments, the stamped part 11 has a generally circular or rectangular shape.

[0030] According to various embodiments, the reinforcing fibers are glass fibers or natural fibers (flax, cotton, hemp, etc.).

[0031] According to various embodiments not shown: • 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, • either said body is devoid of a backing coating layer, said transducer being fixed to the backing reinforcement sheet 8.

[0032] According to various embodiments, the backing layer of the covering is glued or overmolded by the foam of the reinforcing backing sheet 8.

[0033] According to an embodiment not shown, the panel 1 further comprises a face covering layer, for example carpet.

[0034] According to various embodiments, the face covering layer is glued or overmolded by the foam of the face reinforcing ply 7.

[0035] According to various embodiments not shown, the transducer 10 is fixed: • by glue, • and / or by rivets, • and / or by screws, • and / or by fitting into a plate secured to the body 2.

[0036] According to one embodiment, the reinforcing fibers are bonded together by a bonding agent, for example in the form of resin.

[0037] 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.

[0038] According to one embodiment, the pad 15 has a height of less than 3 mm,

[0039] According to one embodiment, the reinforcing plies 7, 8 have a surface mass of between 200 and 500 g / m2.

[0040] A method of manufacturing a panel 1 is now described, in a manner not shown, said method comprising the following steps: • provide a compressible cellular core 3, said core having a face front face 4 and a reverse face 5, said core having open cells 6 opening on either side towards said faces, • arrange two reinforcement layers of front 7 and back 8 on each of said faces, said layers 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 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, • remove the entire said mold and fix a transducer 10 in said stamped part.

[0041] In order to ensure good filling of the core 3 with the foam, it is possible to provide facing the stamped part 11, to have an excess of foam precursor mixture facing the area intended to form said stamped part.

[0042] It is also possible to provide for associating at least one face and / or back layer of covering on at least one reinforcing layer 7, 8, in particular by gluing or by overmolding with the foam in the mold.

Claims

Claims

1. Panel (1) for interior trim 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 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 being characterized in that: • said transducer is fixed in a stamping (11) made in said backing sheet to form a housing for receiving said transducer, said stamping 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 sheets 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 between 50 and 600 cm2.

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, • or said body is devoid of a backing coating layer, said transducer being fixed on the backing reinforcement ply (8).

6. Panel according to any one of the preceding claims, characterized in that the transducer (10) is fixed: • by glue, • and / or by rivets, • and / or by screws, • and / or by fitting into a plate secured 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. A method of manufacturing a panel (1) according to any one of the preceding claims, characterized in that it comprises the following steps: • providing 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, • arranging two front (7) and back (8) reinforcing plies on each of said faces, said plies being based on entangled reinforcing fibers, • pouring onto each of said plies 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 stamped portion (11) on the side of said backing sheet, waiting for the foam to expand so as to form reinforcement front (7) and back (8) sheets impregnated with foam, said foam overmolding said core, so as to associate said sheets with said faces, said foam filling said core opposite said stamped portion, removing the assembly from said mold and fixing a transducer (10) in said stamping.

Images