Floor structure for an electric-powered motor vehicle

Abstract

The invention relates to a floor structure (1) for an electric-powered motor vehicle successively comprising, from bottom to top: a battery (2) arranged in a tray (3), a floor plate (5) facing the battery and an acoustical trim lining (6) arranged on the plate, the structure further comprising a fibrous and porous thermal protection layer (7) arranged between the lining and the plate, the protection layer comprising thermal protection fibres based on at least one fusible material and structural fibres of one or more types, the fibres being infusible or based on a material having a melting point greater than the maximum melting point of the protection fibres.

Description

[0001] DESCRIPTION

[0002] Title: Floor architecture of an electrically powered motor vehicle

[0003] The invention relates to an electrically powered motor vehicle floor architecture, and a method for implementing thermal protection of an acoustic protection and trim lining included in such an architecture.

[0004] It is known to produce an electrically powered motor vehicle floor architecture comprising successively, from bottom to top:

[0005] • a battery placed in a tray,

[0006] • a floor sheet facing said battery,

[0007] • an acoustic protection and cladding lining placed on said sheet metal.

[0008] However, with such an implementation, in the event of overheating of the battery - in particular due to thermal runaway linked to a short circuit, an impact of the vehicle with intrusion of a foreign element into the battery, etc. - there is a risk of propagation of excessive heat towards the sheet metal and the lining, the latter risking catching fire and / or emitting toxic smoke.

[0009] If we wish to thermally protect the lining by adding a means of thermal protection, we are obliged to take into account various constraints:

[0010] • not encroach, or only moderately, on the interior volume of the vehicle,

[0011] • not to degrade, or only moderately, the bearing capacity of the lining provided with the protective means,

[0012] • not degrade, or only moderately, the acoustic protection provided by the lining. The aim of the invention is to propose an architecture making it possible to protect the lining while taking into account the constraints mentioned above.

[0013] To this end, and according to a first aspect, the invention proposes an electrically powered motor vehicle floor architecture comprising successively, from bottom to top:

[0014] • a battery placed in a tray,

[0015] • a floor sheet facing said battery,

[0016] • an acoustic protection and cladding lining arranged on said sheet metal, said architecture further comprising a fibrous and porous thermal protection layer arranged between said lining and said sheet metal, said protective layer comprising:

[0017] • thermal protection fibers based on at least one fusible material,

[0018] • and structural fibers of one or more types, said fibers being infusible or based on material with a melting point higher than the maximum melting point of said protective fibers.

[0019] The reference to the maximum melting point of the protective fibres is used to take into account the case where the protective fibres have two melting points - such as the two-component fibres explained below - or the case of a mixture of protective fibres with different melting points.

[0020] With the proposed arrangement, placing a thermal protection layer under the lining protects it from overheating by means of the fusion of the thermal protection fibers.

[0021] Indeed, fusion corresponds to an endothermic phase change; consequently, part of the heat released by the battery is devoted to the fusion of the protective fibers, which makes it possible to limit the quantity of heat transmitted to the lining. Furthermore, subject to choosing the protective fibers appropriately - in particular by an appropriate choice of their chemical nature, their specific heat capacity, their diameter, we manage to reconcile thermal protection with the above-mentioned constraints:

[0022] • the impact of adding the protective layer on the interior volume available in the vehicle is limited by using a thin protective layer, the thickness of the lining being able to be reduced to free up space for housing said layer,

[0023] • sufficient bearing capacity is maintained for the stack formed by the lining and the protective layer, this making it possible to avoid excessive sinking of the assembly under the weight of a passenger or an object,

[0024] • acoustic protection is preserved; in fact, the fibrous and porous nature of the protective layer gives it acoustic absorption properties in addition to those provided by the lining.

[0025] According to a second aspect, the invention proposes a method for implementing thermal protection of an acoustic protection and cladding lining included in such an architecture.

[0026] Other features and advantages of the invention will appear in the following description, made with reference to the attached figures, in which: [Fig.1] is a schematic representation in partial section of an architecture according to one embodiment,

[0027] [Fig. 2] is a schematic cross-sectional representation of a bi-component fiber.

[0028] With reference to the figures, an architecture 1 of an electrically powered motor vehicle floor is described, comprising successively, from bottom to top:

[0029] • a battery 2 arranged in a container 3, said container being provided in particular with a cover 4 in the embodiment shown,

[0030] • a floor sheet 5 - in particular for the passenger compartment and / or luggage compartment - facing said battery, • an acoustic protection and trim lining 6 arranged on said sheet, said architecture further comprising a fibrous and porous thermal protection layer 7 arranged between said lining and said sheet, said protective layer comprising:

[0031] • thermal protection fibers based on at least one fusible material

[0032] - knowing that infusible additives may be present (talc filler, etc.) -,

[0033] • and structural fibers of one or more types - for example glass fibers or natural fibers -, said fibers being infusible or based on material with a melting point higher than the maximum melting point of said protective fibers.

[0034] According to various embodiments, the floor sheet 2 faces the cover 4 with the interposition, according to the embodiment shown, of an elastically compressible intermediate decoupling layer 8 - for example based on foam - or even an air gap, according to an embodiment not shown.

[0035] The lining 6 may for example comprise, according to the embodiment shown, a layer of covering material 9 - such as a carpet - and an elastically compressible decoupling layer 10 - in particular based on foam and / or fibers.

[0036] According to one embodiment, the protective fibers are, at least in part, of the single-component type, said fibers being based on a single fusible material, for example polypropylene, polyamide or polyethylene terephthalate.

[0037] According to an embodiment illustrated in figure 2, the protective fibers are, at least in part, of the two-component type 11, said fibers comprising a sheath 12 based on a first fusible material and a core 13 based on a second fusible material, the melting point of said first material being lower than that of said second material, said sheath ensuring, following its melting - for example following thermocompression - the connection between the fibers of the protective layer 7.

[0038] With such an arrangement, melting of the sheath 12 can be observed only in the event of a moderate rise in temperature, or successively of said sheath then of the core 13 in the event of a greater rise in temperature.

[0039] According to various embodiments, the core 13 is based on polyethylene terephthalate and the sheath 12 is based on modified polyethylene terephthalate or polyethylene.

[0040] According to one embodiment, the protective layer 7 comprises at least two types of protective fibers which fuse at different temperatures, so as to allow stepwise melting of said layer.

[0041] With such an implementation, if the temperature is not too high, the most temperature-resistant fibers remain intact and therefore contribute, with the structural fibers, to the structure of the protective layer 7.

[0042] According to one embodiment, the resistance to the passage of air of the protective layer 7 is less than 6000 Nsm -3 , for example between 3000 and 4000 Nsnr 3, which ensures sound absorption and limits the negative influence of a high Young's modulus on sound protection performance.

[0043] According to one embodiment, the Young's modulus in compression of the protective layer 7 is greater than 35 MPa, which ensures satisfactory load-bearing.

[0044] According to one embodiment, the thermal conductivity of the protective layer 7 between -40 and +45°C is between 0.03 and 0.12 W.m' 1 .K' 1 .

[0045] According to an embodiment not shown, the protective layer 7 is single-layer, the protective fibers - whether of one or more types - and structural fibers being mixed together. According to the embodiment shown in FIG. 1, the protective layer 7 comprises a plurality of sub-layers 7a, 7b each comprising protective fibers mixed with structural fibers.

[0046] According to an embodiment not shown, the architecture 1 further comprises a thermal insulation layer, for example based on cork, arranged between the sheet 5 and the protective layer 7, which makes it possible to reinforce the thermal protection.

[0047] According to one embodiment, the protective layer 7 has a thickness of between 4 and 8 mm.

[0048] According to one embodiment, the protective layer 7 is needled.

[0049] According to one embodiment, the protective layer 7 has undergone a hot compression operation, certain areas - for example "foot cellars" - may have been subject to over-compression, to increase their load-bearing capacity.

[0050] According to one embodiment, the percentage by mass of the protective fibers 7 is between 60 and 90% by mass of said layer.

[0051] Finally, a method is described for implementing thermal protection of a lining 6 for acoustic protection and cladding included in the architecture 1, said lining being intended to be arranged on a floor sheet 5 of said vehicle, said method providing for arranging, between said sheet and said lining, a fibrous and porous thermal protection layer 7 comprising:

[0052] - thermal protection fibers based on at least one fusible material,

[0053] - and structural fibers of one or more types, said fibers being infusible or based on material with a melting point higher than the maximum melting point of said protective fibers.

Claims

DEMANDS 1. Architecture (1) of an electric motor vehicle floor comprising successively, from bottom to top: • a battery (2) arranged in a container (3), • a floor plate (5) facing said battery, • an acoustic protection and cladding lining (6) disposed on said sheet metal, said architecture being characterized in that it further comprises a fibrous and porous thermal protection layer (7) disposed between said lining and said sheet metal, said protection layer comprising: • thermal protection fibers made from at least one fusible material, • and structural fibers of one or more types, said fibers being infusible or based on material with a melting point higher than the maximum melting point of said protective fibers.

2. Architecture according to claim 1, characterized in that the protective fibers are, at least in part, of a single-component type, said fibers being based on a single fusible material.

3. Architecture according to any one of the preceding claims, characterized in that the protective fibers are, at least in part, of a two-component type (11), said fibers comprising a sheath (12) based on a first fusible material and a core (13) based on a second fusible material, the melting point of said first material being lower than that of said second material, said sheath ensuring, following its melting, the bond between the fibers of the protective layer (7)- 4. An architecture according to any one of the preceding claims, characterized in that the protective layer (7) comprises at least two types of fusible protective fibers at different temperatures, so as to allow a stepwise melting of said layer.

5. An architecture according to any one of the preceding claims, characterized in that the air permeability of the protective layer (7) is less than 6000 Nsnr 3 .

6. Architecture according to any one of the preceding claims, characterized in that the Young's modulus in compression of the protective layer (7) is greater than 35 MPa.

7. Architecture according to any one of the preceding claims, characterized in that the thermal conductivity of the protective layer (7) between -40 and +45°C is between 0.03 and 0.12 W.m' 1 .K' 1 .

8. Architecture according to any one of claims 1 to 7, characterized in that the protective layer (7) is single-layer, the protective and structural fibers being mixed together.

9. Architecture according to any one of claims 1 to 7, characterized in that the protective layer (7) comprises a plurality of sublayers (7a, 7b) each comprising protective fibers mixed with structural fibers.

10. Method of implementing thermal protection for a soundproofing and trim lining (6) included in an architecture (1) according to any one of the preceding claims, said lining being intended to be placed on a floor plate (5) of said vehicle, said method providing for placing, between said plate and said lining, a fibrous and porous thermal protection layer (7) comprising: - thermal protection fibers made from at least one fusible material, - and structural fibers of one or more types, said fibers being infusible or based on material with a melting point higher than the maximum melting point of said protective fibers.

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