Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
  • B60R13/00—Elements for body-finishing, identifying, or decorating; Arrangements or adaptations for advertising purposes
  • B60R13/08—Insulating elements, e.g. for sound insulation
  • B60R13/0815—Acoustic or thermal insulation of passenger compartments

Definitions

• the invention relates to an acoustic and thermal protection screen for a motor vehicle, an assembly of such a screen and a method for producing such a screen.
• said spring layer comes from reaction injection molding (RIM), said layer overmolding a reverse side of said shell,
• said shell has a porosity arranged to allow said foam to create a tight skin on the side of said face, by penetration of foam into a fraction of the thickness of said shell, so that said screen is acoustically insulating, according to a principle "mass-spring" - implementing a mass layer, formed by said shell provided with said waterproof skin, and said spring layer -, said screen also having sound absorption properties conferred by the fraction of thickness of said shell not penetrated by said foam and remaining porous.
• the thick fibers mentioned above have a large section, for example of the order of 25 microns in the case of glass fibers. With the use of such fibers, one observes, in particular in the most stretched zones of the hull, a significant penetration of the foam within the hull, said penetration being able to take place according to the totality of the thickness of said hull in the most stretched areas.
• the invention aims to minimize as much as possible the penetration of the foam within the shell in order to maximize the sound absorption properties of the screen, and also to minimize its weight and cost.
• the invention proposes an acoustic and thermal protection screen for a motor vehicle, said screen comprising:
• said spring layer comes from reaction injection molding (RIM), said layer overmolding a reverse side of said shell,
• said shell has a porosity arranged to allow said foam to create a tight skin on the side of said face, knowing that:
• said fibers are composed of two types of fibers: o thick reinforcing fibers present at 25 to 40% by weight of said shell, o fine fibers present at 15 to 35% by weight of said shell, • the bonding agent is formed by fusible bonding fibers present at 35 to 50% by weight of said shell, so that said shell is substantially free of penetration of foam in its thickness.
• the presence of fine fibers in the composition of the shell makes it possible to block the penetration of foam within said shell, which makes it possible to maximize the sound absorption properties of the screen, and also minimize its weight and cost.
• the invention proposes an assembly of such a screen and a method of manufacturing such a screen.
• FIG.1 is a schematic sectional view of a screen assembly, according to one embodiment, on a component to be protected,
• FIG.2 is a graphic representation of the sound absorption performance (alpha coefficient on the ordinate) as a function of the 1/3 octave frequency in Hertz, in diffuse field, of a sample from a screen according to the invention (curve 1), the composition of which is specified below, and another sample from a reference screen (curve 2) according to the prior art, the composition of which is also specified below.
• an acoustic and thermal protection screen 1 for a motor vehicle comprising:
• said spring layer comes from reaction injection molding (RIM), said layer overmolding a reverse side of said shell,
• said shell has a porosity arranged to allow said foam to create a sealed skin 5 on the side of said face, said screen being characterized in that:
• said fibers are composed of two types of fibers: o thick reinforcing fibers present at 25 to 40% by weight of said hull, o fine fibers, that is to say having in particular an average diameter which is less than the average diameter of the thick fibers, present at 15 to 35% by weight of said shell,
• the bonding agent is formed by fusible bonding fibers present at 35 to 50% by weight of said hull, so that said hull is substantially free of foam penetration in its thickness.
• the fraction of thickness 4 of shell 2 penetrated by the foam is less than 0.5 mm, and in particular less than 0.2 mm.
• the reinforcing fibers are:
• PET polyethylene terephthalate
• the fine fibers are based on polyethylene terephthalate (PET) with a titer of between 1.5 and 3.3 dtex, and in particular with a titer substantially equal to 1.7 dtex, corresponding to a diameter of 12 microns.
• PET polyethylene terephthalate
• the connecting fibers are:
• polypropylene fibers in particular with a title of between 6 and 7 dtex, said title being in particular 6.7 dtex, corresponding to a diameter of 31 microns,
• • and/or two-component fibers comprising a core with a high melting point and a sheath with a lower melting point, said sheath providing the connection between the fibers following its fusion.
• the two-component fibers comprise a polyethylene terephthalate (PET) core, with a melting point of the order of 250° C., and the sheath is made of polyethylene terephthalate (PET) having undergone a chemical modification so as to present a lowered melting point, for example of the order of 180°C.
• PET polyethylene terephthalate
• PET polyethylene terephthalate
• the shell 2 may typically have a thickness of between 2 and 3 mm.
• the shell 2 may be provided, on at least one of its faces, with a nonwoven protective layer.
• Such a protective layer has in particular a surface mass of between 15 and 120 g/m 2 and in particular a resistance to the passage of air of between 50 and 180 Nsnr 3 .
• a protective layer facing the spring layer 3 does not prevent the formation of the watertight skin 5 opposite the back of the shell 2.
• the front face 9 of the shell 2 - that is to say that opposite the back face - is covered with a coating layer, for example based on fabric.
• shell composition 2 which made it possible to carry out the invention are given below.
• the constituent fibers of the shell 2 are distributed according to the following percentages by weight:
• the constituent fibers of the shell 2 are distributed according to the following percentages by weight:
• binding fibers in particular polypropylene or bi-component - providing a bond between the fibers of said shell following their at least partial fusion.
• the constituent fibers of the shell 2 are distributed according to the following percentages by weight:
• the samples tested all have a thickness of 4 mm and a surface mass of 1000 g/m 2 .
• a noticeable penetration of foam into the shell 2 is observed on the reference sample, in particular in the most stretched zones, whereas the samples from shells 2 made according to the invention are visually free of foam penetration.
• curve 1 • a sample from a shell 2 according to the invention (curve 1), whose composition is: 35% of thick glass fibers with a diameter of 24 microns, 20% of fine PET fibers with a title of 1.7 dtex and 45 % of polypropylene binder fibers with a count of 6.7 dtex,
• the samples tested both have a thickness of 4 mm and a surface mass of 1000 g/m 2 .

Landscapes

• Physics & Mathematics (AREA)
• Acoustics & Sound (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Laminated Bodies (AREA)
• Vehicle Interior And Exterior Ornaments, Soundproofing, And Insulation (AREA)
• Injection Moulding Of Plastics Or The Like (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=78049309

Family Applications (1)

Country Status (4)

Family Cites Families (5)

• 2021
  • 2021-06-29 FR FR2107000A patent/FR3124449A1/fr active Pending
• 2022
  • 2022-06-28 WO PCT/EP2022/067775 patent/WO2023275077A1/fr active Application Filing
  • 2022-06-28 EP EP22735453.7A patent/EP4363275A1/de active Pending
  • 2022-06-28 CN CN202280051862.XA patent/CN117836178A/zh active Pending

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