Seat trim element for a motor vehicle

Abstract

The invention relates to a seat trim element (1) for a motor vehicle, the element comprising a block (2) having a receiving face (3) and a cavity (4) having an opening (5), a plate (6) attached at the periphery of the opening, and an inertial electrodynamic transducer (9) for vibrating the plate, wherein the element further comprises a sealed wall (17) for acoustic insulation arranged over the entire outer surface of the block, wherein the wall has a receiving portion (14) extending opposite the receiving face, and a complementary portion (15) formed by the remainder of the wall, wherein the material of the receiving portion is elastically compressible, and wherein the material has a Shore hardness of less than 25 Shore A and a compressive Young's modulus of less than 5 MPa.

Description

[0001] DESCRIPTION

[0002] Title: Motor vehicle seat trim element

[0003] The invention relates to a motor vehicle seat trim element.

[0004] It is known to produce a trim element - such as a headrest, a backrest or part of a backrest - for a motor vehicle seat, said element comprising:

[0005] • a padding block made of elastically compressible air-porous material, said block having a face for receiving an occupant of said seat, said block being provided with a cavity having an opening opening towards said receiving face,

[0006] • a rigid plate fixed by its periphery, by means of a decoupling means, on the periphery of said opening so as to conceal it, said plate having an internal face turned towards said cavity,

[0007] • an inertial electrodynamic transducer comprising a coil and a magnet fixed on a support, said support being mounted by means of a suspension means integrally with said coil, so that said plate begins to vibrate when said transducer is powered, said coil being fixed on said internal face.

[0008] As a reminder, transduction is the operation allowing one physical quantity to be transformed into another, this 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 rigid plate on which the transducer is fixed, for example in order to deliver a sound audible by an occupant of the seat (music, message, etc.) or even a sound signal in phase opposition with the sound signal corresponding to the noise in the passenger compartment when the vehicle is moving. It is recalled here that a transducer differs from a loudspeaker in the following way:

[0010] • 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,

[0011] • 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 energized.

[0012] 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.

[0013] In addition, the use of a transducer is advantageous because it takes up less space and weighs less than a loudspeaker.

[0014] However, with the embodiment of the prior art described above, the problem arises of having a closed "acoustic loading cavity" - that is to say a cavity where the acoustic waves coming from the transducer are channeled by the opening of said cavity -, in order to allow optimization of the transmission of said acoustic waves.

[0015] In addition, it is imperative to preserve the comfort of a seat occupant facing the receiving face of the block.

[0016] The invention aims to propose an arrangement that makes it possible to meet these expectations.

[0017] To this end, the invention proposes a motor vehicle seat upholstery element, said element comprising: • a padding block made of elastically compressible air-porous material, said block having a face for receiving an occupant of said seat, said block being provided with a cavity having an opening opening towards said receiving face,

[0018] • a rigid plate fixed by its periphery, by means of a decoupling means, on the periphery of said opening so as to conceal it, said plate having an internal face facing said cavity,

[0019] • an inertial electrodynamic transducer comprising a coil and a magnet fixed to a support, said support being mounted by means of a suspension means integrally with said coil, so that said plate begins to vibrate when said transducer is powered, said coil being fixed to said internal face, said element further having the following characteristics:

[0020] • it further comprises a sealed acoustic insulation wall arranged over the entire external surface of said block, so as to channel the passage of acoustic waves from said transducer through said opening, said wall having a receiving part extending opposite said receiving face, the remainder of said wall forming a complementary part of said receiving part,

[0021] • the material of said receiving part is elastically compressible, its shore hardness being less than 25 shore A and its Young's modulus in compression being less than 5 MPa.

[0022] It is specified here that when it is said that the waterproof acoustic insulation wall is arranged over the entire external surface of the block, it should be understood that said wall does not extend over the opening of the cavity.

[0023] With the proposed arrangement, the presence of the sealed acoustic insulation wall arranged over the entire external surface of the block makes it possible to channel the passage of acoustic waves from said transducer through the opening, in other words to close the "acoustic loading cavity". In addition, the use of a material such as defined above to produce the receiving part is conducive, due to the flexibility of said material, to optimizing the comfort of a seat occupant.

[0024] Other features and advantages of the invention will appear in the following description, given with reference to the attached figures, in which:

[0025] [Fig.1] is a schematic sectional view of an embodiment of a seat back provided with two upholstery elements arranged laterally on either side,

[0026] [Fig .2] is a detail view of figure 1,

[0027] [Fig.3] is a schematic sectional view of a transducer according to one embodiment, said transducer being fixed on a plate.

[0028] With reference to the figures, a motor vehicle seat upholstery element 1 is described, said element comprising:

[0029] • a block 2 of padding made of elastically compressible air-porous material, said block having a receiving face 3 for an occupant of said seat, said block being provided with a cavity 4 having an opening 5 opening towards said receiving face,

[0030] • a rigid plate 6 fixed by its periphery, by means of a decoupling means 7 - for example in the form of a rubber or flexible foam seal -, on the periphery of said opening so as to conceal it, said plate having an internal face 8 facing said cavity,

[0031] • an inertial electrodynamic transducer 9 comprising a coil 10 and a magnet 11 fixed to a support 12 - in particular made of molded plastic material -, said support being mounted by means of a suspension means 13 integrally with said coil, so that said plate begins to vibrate when said transducer is powered, said coil being fixed to said internal face, said element furthermore having the following characteristics:

[0032] • it further comprises a sealed acoustic insulation wall 17 arranged over the entire external surface of said block - said wall being for example glued to said block or inserted between said block and a cover as described below - so as to channel the passage of acoustic waves from said transducer through said opening, said wall having a receiving part 14 extending opposite said receiving face, the rest of said wall forming a complementary part 15 of said receiving part,

[0033] • the material of said receiving part is elastically compressible, its shore hardness being less than 25 shore A and its Young's modulus in compression being less than 5 MPa.

[0034] Shore A hardness measurement is carried out in particular according to the ISO 7619-1 standard.

[0035] According to various embodiments, the material of the complementary part 15 is optional:

[0036] • identical to that of the receiving part 14,

[0037] • or partly identical to that of said receiving part and partly different - being for example based on thermoplastic elastomer - from that of said receiving part,

[0038] • or different - for example being based on thermoplastic elastomer - from that of said receiving part.

[0039] According to one embodiment, the receiving part 14 has a thickness of between 1 and 20 mm, so as to ensure comfort adapted to an occupant of the seat.

[0040] According to one embodiment, the material of the receiving part 14 is a closed-cell foam.

[0041] According to one embodiment, the foam forming the material of the receiving part 14 has a density of between 100 and 1500 kg / m 3 .

[0042] According to an embodiment not shown, the padding block 2 provided with the waterproof wall 17 is covered at least in part by a covering cap - for example based on textile or leather provided with a soft foam underlayer -, said cap having, at least opposite the plate 6, a resistance to the passage of air of less than 200 Nsnr 3 , so as to allow the propagation of acoustic waves.

[0043] According to the embodiment shown, the plate 6 is covered with a layer of comfort foam 16 with a resistance to the passage of air of less than 200 Nsnr 3 , so as to allow the propagation of acoustic waves; such a layer of comfort foam 16 can in particular be inserted between the plate 6 and a cover as described above.

[0044] According to one embodiment, the padding block 2 is made of foam - in particular polyurethane - molded with a density of between 30 and 80 kg / m 3.

Claims

CLAIMS 1. Element (1) for upholstering a motor vehicle seat, said element comprising: • a block (2) of padding made of elastically compressible air-porous material, said block having a receiving face (3) for an occupant of said seat, said block being provided with a cavity (4) having an opening (5) opening towards said receiving face, • a rigid plate (6) fixed by its periphery, by means of a decoupling means (7), on the periphery of said opening so as to conceal it, said plate having an internal face (8) facing said cavity, • an inertial electrodynamic transducer (9) comprising a coil (10) and a magnet (11) fixed on a support (12), said support being mounted by means of a suspension means (13) integrally with said coil, so that said plate begins to vibrate when said transducer is powered, said coil being fixed on said internal face, said element being characterized in that: • it further comprises a sealed acoustic insulation wall (17) arranged over the entire external surface of said block, so as to channel the passage of acoustic waves from said transducer through said opening, said wall having a receiving part (14) extending opposite said receiving face, the remainder of said wall forming a complementary part (15) of said receiving part, • the material of said receiving part is elastically compressible, its shore hardness being less than 25 shore A and its Young's modulus in compression being less than 5 MPa.

2. Element (1) according to claim 1, characterized in that the material of the complementary part (15) is either: • identical to that of the receiving part (14), • or partly identical to that of the said receiving part and partly different from that of the said receiving part, • or different from that of the said receiving party.

3. Element (1) according to one of the preceding claims, characterized in that the receiving part (14) has a thickness of between 1 and 20 mm.

4. Element (1) according to any one of the preceding claims, characterized in that the material of the receiving part (14) is a closed-cell foam.

5. Element (1) according to the preceding claim, characterized in that the foam forming the material of the receiving part (14) has a density of between 100 and 1500 kg / m 3 .

6. Element (1) according to any one of the preceding claims, characterized in that the padding block (2) provided with the sealed wall (17) is covered at least in part by a covering cap, said cap having, at least opposite the plate (6), a resistance to the passage of air of less than 200 Nsm. -3 , so as to allow the propagation of acoustic waves.

7. Element (1) according to any one of the preceding claims, characterized in that the plate (6) is covered with a layer of comfort foam (16) with resistance to the passage of air of less than 200 Nsm. -3 , so as to allow the propagation of acoustic waves.

8. Element (1) according to any one of the preceding claims, characterized in that the padding block (2) is made of molded foam with a density of between 30 and 80 kg / m 3 .

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