Composite floor and motor vehicle comprising such a floor

0001The invention generally relates to motor vehicle floors.

0002More specifically, according to a first aspect, the invention relates to a motor vehicle floor, of the type comprising: <ul id="ul0001" list-style="none"><li id="ul0001-0001" num="0000"><ul id="ul0002" list-style="none"><li id="ul0002-0001" num="0003">a lower floor made from a composite material; and</li><li id="ul0002-0002" num="0004">an upper floor made from a composite material, extending across from at least part of the lower floor, the lower and upper floors being connected to one another.</li></ul></li></ul>

0005Floors of this type are known, for example from FR 2,912,108. Such floors are light, but are not completely satisfactory in terms of space optimization when functional elements are integrated into the lower and upper floors. Furthermore, floors of this type do not have satisfactory sound insulation.

0006In this context, the invention aims to propose a motor vehicle floor allowing optimized integration of functional elements and having optimized soundproofing and that in particular attenuates noise related to the exhaust line of the vehicle.

0007To that end, the invention relates to a floor of the aforementioned type, characterized in that the floor comprises at least one cavity at least partially delimited by the lower or upper floor and communicating with the exhaust line of the motor vehicle.

0008Advantageously, the floor comprises one or more cavities delimited by the lower floor and the upper floor. This or these cavities may favorably be used to form an exhaust volume, for example. The space is thus used optimally, and the soundproofing is improved. This or these cavities may favorably be used to integrate an acoustic damping system for exhaust noises, for example a Helmholtz system, here called resonator. The integration of such a resonator-forming cavity in the floor of the vehicle makes it possible to very significantly attenuate noises related to the exhaust line, without increasing the bulk of the floor.

0009The upper floor is typically turned toward the inside of the passenger compartment of the vehicle. On the contrary, the lower floor is traditionally turned toward the rolling surface of the vehicle.

0010The composite material forming the upper floor comprises long fibers. Alternatively, it comprises short fibers. The fibers are for example glass fibers and/or carbon fibers and/or aramid fibers and/or natural fibers. These fibers are embedded in a thermoplastic and/or thermoset and/or vitremer resin, for example polyamide, polypropylene, polyester or epoxy.

0011The composite material of the upper floor has a thickness comprised between 1 mm and 6 mm, and preferably equal to 2 mm.

0012The composite material of the lower floor is for example identical to the composite material of the upper floor. Alternatively, it is different. It also includes long or short fibers, for example glass fibers and/or carbon fibers and/or aramid fibers and/or natural fibers. These fibers are embedded in a thermoplastic and/or thermoset and/or vitremer resin, for example polyamide, polypropylene, polyester or epoxy. The composite material of the lower floor has a thickness comprised between 1 mm and 6 mm, preferably equal to 2 mm.

0013The upper floor extends opposite at least part of the lower floor. For example, it extends opposite at least 60% of the surface of the lower floor.

0014The upper floor and the lower floor are connected to one another, either directly or by means of an external connecting part, for example made from composite material. They are glued, welded or mechanically assembled to one another by one or more fastening members, for example one or more rivets.

0015In a first alternative embodiment, the cavity is delimited by the lower floor and the upper floor, i.e., all of the walls delimiting the cavity belong to the lower and upper floors.

0016In this alternative, the cavity makes it possible to significantly decrease the noises related to the exhaust line, but without increasing the bulk of the floor of the vehicle. Furthermore, it makes it possible to avoid the bulk of the floor. Additionally, it does not require additional material for its manufacture, and thereby favors lightening of the vehicle.

0017According to a second alternative embodiment, the floor comprises a shell, the lower floor comprising a lower face and an upper face, the upper face extending opposite the upper floor, the shell being fastened on the lower face, the cavity being delimited by the lower floor and by the shell. The shell is for example fastened to the lower floor by removable mechanical fastening means, such as screws. In this alternative, the cavity is easy to disassemble, and can thus easily be repaired or exchanged, for example when it is damaged.

0018In this second alternative, the shell is made from metal. The metal of the shell is for example steel or aluminum. The metal of the shell has a thickness comprised between 0.5 mm and 3 mm, preferably equal to 1.5 mm.

0019Alternatively, the shell is a plastic having temperature resistance characteristics adapted to an exhaust line.

0020Alternatively, the shell is made from a composite material. The composite material of the shell is for example identical to the composite material of the lower floor and/or the upper floor. Alternatively, it is different. It includes long fibers or short fibers, for example glass fibers and/or carbon fibers and/or aramid fibers and/or plant fibers. These fibers are embedded in a thermoplastic or thermoset or vitremer resin, for example polyamide, polypropylene, polyester or a proxy. The composite material of the shell has a thickness comprised between 1 mm and 6 mm, and preferably equal to 2 mm.

0021In order to reduce the temperature of the floor and protect the latter, the cavity for example comprises a thermally insulating inner coating. This is for example a specific surface treatment, or an external attached part acting as a thermal insulator.

0022In the event the cavity forms a resonator, the cavity further comprises a fluidic communication member between the cavity and the exhaust line of the motor vehicle, for example a tube. Preferably, the cavity includes a single fluid communication member, for example a single tube. The Helmholtz resonator-forming cavity makes it possible to absorb part of the acoustic excitation coming from the exhaust line. This Helmholtz resonance phenomenon favors the acoustic weakening of the noises related to the exhaust line.

0023Furthermore, the design of the connecting tube is such that there is no permanent flow of exhaust gas from the main line toward the resonator.

0024The heating of the resonator is therefore limited.

0025The fluidic communication member is made from a metal, such as steel or aluminum. Alternatively, it is at least partially made from a composite material. The composite material of the fluidic communication member includes long fibers or short fibers, for example glass fibers and/or carbon fibers and/or aramid fibers and/or plant fibers. These fibers are embedded in a thermoplastic or thermoset or vitremer resin, for example polyamide, polypropylene, polyester or a proxy.

0026The exhaust line being mobile and the cavity formed by the floor being stationary, the fluidic communication member advantageously comprises an uncoupling element able to attenuate vibrations and movements of the exhaust line.

0027According to one advantageous feature of the invention, the floor further includes at least one hollow body delimited by the lower floor and the upper floor. It is then advantageous to take advantage of the space available in the hollow body, for example to house a soundproofing layer, making it possible to still further improve the soundproofing of the vehicle. Alternatively, the hollow body incorporates other functional elements, such as stiffening profiles, cables, ventilation sheaths, metal anchoring reinforcing inserts, for example for a seat.

0028According to a second aspect, the invention relates to a motor vehicle comprising: <ul id="ul0003" list-style="none"><li id="ul0003-0001" num="0000"><ul id="ul0004" list-style="none"><li id="ul0004-0001" num="0029">a chassis;</li><li id="ul0004-0002" num="0030">a floor as described above, rigidly fastened to the chassis.</li></ul></li></ul>

0031The motor vehicle is for example a car or utility vehicle, or a truck.

0032The floor is typically a rear floor, which extends between the heel board and the rear crossmember of the vehicle. Alternatively, the floor is a front floor, which extends between the firewall of the vehicle and the heel board. Alternatively, the floor extends between the firewall of the vehicle and the rear crossmember of the vehicle. The firewall is a partition separating the engine compartment of the vehicle from the passenger compartment. The floor is rigidly fastened not only to the longitudinal beams of the vehicle, but also potentially to the firewall, the rear crossmember and/or the heel board.

0033Other features and advantages of the invention will emerge from the detailed description thereof provided below, for information and non-limitingly, in reference to the appended figures, in which:

0034<figref idref="DRAWINGS">FIG. 1</figref> is a simplified diagrammatic illustration of a motor vehicle including a floor according to a first embodiment of the invention;

0035<figref idref="DRAWINGS">FIG. 2</figref> is a longitudinal sectional view of the floor of <figref idref="DRAWINGS">FIG. 1</figref>;

0036<figref idref="DRAWINGS">FIG. 3</figref> is a longitudinal sectional view of a floor according to a second embodiment of the invention;

0037<figref idref="DRAWINGS">FIG. 4</figref> is a longitudinal sectional view of the cavity of the floor of <figref idref="DRAWINGS">FIG. 3</figref>.

0038In the rest of the description, the longitudinal, transverse, vertical, front and rear directions will be defined in reference to the normal movement direction of the motor vehicle. The vertical direction here is taken to be the perpendicular to the rolling plane of the vehicle.

0039The vehicle <b>2</b> shown in <figref idref="DRAWINGS">FIG. 1</figref> comprises a body delimiting, in the vehicle, a passenger compartment <b>4</b>, an engine compartment <b>6</b> situated in front of the passenger compartment, and a rear crossmember <b>8</b> delimiting a trunk <b>10</b> situated behind the passenger compartment. The engine compartment <b>6</b> is separated from the passenger compartment by a firewall <b>12</b>. The passenger compartment is downwardly delimited by a floor <b>14</b>. The floor <b>14</b> includes a rear floor <b>16</b>, which will be described below, and a front floor <b>18</b>. The rear floor <b>16</b> and the front floor <b>18</b> are connected to one another in a zone <b>19</b> situated between a transverse crossmember traditionally called “heel board” and the rear support crossmember of the seats. This connecting zone is commonly called “backseat foot well 2”.

0040The vehicle further includes seats <b>20</b>, <b>21</b> that are rigidly fastened, directly or indirectly, to the floor <b>14</b>. The front floor <b>18</b> is fastened at the front to the firewall <b>12</b> and supports the seats <b>20</b> situated in the front of the vehicle. The rear floor <b>16</b> is fastened at the rear to the rear crossmember <b>8</b>, and supports the seats <b>21</b> situated in the back of the vehicle, and the trunk <b>10</b>.

0041The floor <b>14</b> of the vehicle extends from the firewall <b>12</b> to the rear crossmember <b>8</b> in the longitudinal direction of the vehicle, and extends transversely substantially over the entire width of the vehicle. It is laterally rigidly fastened on the chassis (not shown), more specifically on the side beams of the vehicle <b>2</b>.

0042<figref idref="DRAWINGS">FIGS. 2 and 3</figref> show the rear floor <b>16</b> of the floor <b>14</b> according to the invention. The rear floor <b>16</b> comprises: <ul id="ul0005" list-style="none"><li id="ul0005-0001" num="0000"><ul id="ul0006" list-style="none"><li id="ul0006-0001" num="0043">a lower floor <b>22</b> made from a composite material;</li><li id="ul0006-0002" num="0044">an upper floor <b>24</b> made from a composite material, extending opposite from at least part of the lower floor <b>22</b>;</li><li id="ul0006-0003" num="0045">a cavity <b>26</b> communicating with the exhaust line <b>27</b> of the vehicle and at least partially delimited by the lower floor <b>22</b>; and</li><li id="ul0006-0004" num="0046">optionally, a hollow body <b>28</b> comprising a separate layer <b>30</b> and/or a layer of structural foam <b>35</b>.</li></ul></li></ul>

0047The rear floor <b>16</b> further comprises mechanical reinforcements <b>31</b>, and optionally a housing <b>33</b> for example for a repair kit or battery (not shown), delimited by the lower floor <b>22</b>.

0048The lower floor <b>22</b> comprises a lower face <b>32</b> and an upper face <b>34</b>. The upper face <b>34</b> extends opposite the upper floor <b>24</b>, and the lower face <b>32</b> faces the rolling surface of the vehicle. The lower face <b>32</b> defines an outer surface of the vehicle, exposed to the atmosphere.

0049The upper floor <b>24</b> extends longitudinally over part of the lower floor <b>22</b>. For example, the upper floor <b>24</b> faces 60% of the surface of the lower floor <b>22</b>.

0050The lower floor <b>22</b> and the upper floor <b>24</b> are assembled to one another by gluing and/or welding and/or any other mechanical fastening means.

0051Alternatively, or in addition to the layer of glue, the lower and upper floors <b>22</b>, <b>24</b> are rigidly fastened to one another by a plurality of fastening members <b>36</b>, <b>38</b>, <b>40</b>, <b>42</b>, such as self-tapping rivets, as shown in <figref idref="DRAWINGS">FIG. 2</figref>, and/or by a continuous or discontinuous weld line. The fastening members <b>36</b>, <b>38</b>, <b>40</b>, <b>42</b> are regularly distributed along the rear floor <b>16</b>. Only four fastening members <b>36</b>, <b>38</b>, <b>40</b>, <b>42</b> are shown in <figref idref="DRAWINGS">FIG. 2</figref>, but alternatively, the rear floor <b>16</b> comprises other fastening members that are not shown.

0052The cavity <b>26</b> is delimited by the lower floor <b>22</b> and the upper floor <b>24</b>. More specifically, the cavity <b>26</b> is delimited by a peripheral wall <b>44</b>, an upper wall <b>48</b> and a bottom wall <b>50</b>. The peripheral wall <b>44</b> and the bottom wall <b>50</b> are formed in the lower floor <b>22</b>. The upper wall <b>48</b> is formed in the upper floor <b>24</b>. Advantageously, fastening members, for example two fastening members <b>40</b>, <b>42</b>, are distributed around the cavity <b>26</b> so as to rigidly keep the lower <b>22</b> and upper <b>24</b> floors attached near the cavity <b>26</b>. A seal (not shown) is inserted between the lower <b>22</b> and upper <b>24</b> floors around the cavity <b>26</b> to create tightness.

0053The cavity <b>26</b> comprises a single communication tube <b>52</b>. In the example shown in the figures, the communication tube <b>52</b> extends substantially in the plane formed by the vertical and longitudinal directions. The tube <b>52</b> is attached to the cavity <b>26</b> and is glued or welded, for example, to the bottom wall <b>50</b> and the peripheral wall <b>44</b>. Alternatively, the tube <b>52</b> is integral with the bottom of <b>50</b> and the peripheral wall <b>44</b>. It connects the cavity <b>26</b> to the exhaust line <b>27</b> of the vehicle. The tube advantageously comprises an uncoupling element <b>53</b> visible in <figref idref="DRAWINGS">FIG. 1</figref>. The uncoupling element <b>53</b> makes it possible to attenuate vibrations and movements of the exhaust line <b>27</b>.

0054The hollow body <b>28</b> is delimited by the lower floor <b>22</b> and the upper floor <b>24</b>. The hollow body <b>28</b> for example comprises a soundproofing layer <b>30</b>. The soundproofing layer completely occupies the inner volume of the hollow body <b>28</b>. Alternatively, the sound proofing layer <b>30</b> occupies only part of the inner volume of the hollow body <b>28</b>.

0055Alternatively, the hollow body <b>28</b> comprises a semi-structural or structural foam <b>35</b>, such as a polyamide (PA) foam, a polyethylene terephthalate (PET) foam, an expanded polypropylene (EPP) foam, or a polymethacrylimide (PMI) foam.

0056The mechanical reinforcements <b>31</b> extend along the lower and upper floors <b>22</b>, <b>24</b>. For example and as shown in <figref idref="DRAWINGS">FIG. 2</figref>, a first mechanical reinforcement <b>54</b> includes a first reinforcing plate <b>54</b> that extends along part of the lower floor <b>22</b> and that mates with the shape thereof. The first reinforcing plate <b>54</b> for example has an Ω shape. The first reinforcing plate <b>54</b> is for example glued or welded below the lower floor <b>22</b>. Alternatively (not shown), the first mechanical reinforcement <b>54</b> is integrated into the lower floor <b>22</b> and is formed by an overthickness of the lower floor <b>22</b>.

0057As shown in <figref idref="DRAWINGS">FIG. 2</figref>, a second mechanical reinforcement <b>56</b> includes a second reinforcing plate <b>56</b> that extends along part of the upper floor <b>24</b> and that mats with the shape thereof. The second reinforcing plate <b>56</b> is for example glued or welded to the upper floor <b>24</b>. Alternatively (not shown), the second mechanical reinforcement <b>56</b> is integrated into the lower floor <b>24</b> and is formed by an overthickness of the lower floor <b>22</b>.

0058The first and second mechanical reinforcements <b>54</b>, <b>56</b> extend opposite one another, for example around parts of the lower <b>22</b> and upper <b>24</b> floors delimiting the hollow body <b>28</b>. The first reinforcing plate <b>54</b> extends along the lower floor <b>22</b>, and the second reinforcing plate <b>56</b> extends along the upper floor <b>24</b>, opposite the first reinforcing plate <b>54</b>. Only two mechanical reinforcements <b>31</b> are shown in <figref idref="DRAWINGS">FIG. 2</figref>, but alternatively, the rear floor <b>16</b> comprises other mechanical reinforcements that are not shown.

0059A second embodiment will now be described, in reference to <figref idref="DRAWINGS">FIGS. 3 and 4</figref>. Only the points by which the second embodiment of the invention differs from the first will be outlined below. Identical elements, or elements performing the same function, will be designated using the same references in both embodiments.

0060In the second embodiment, the cavity <b>26</b> is formed by the lower floor <b>22</b> and by a shell <b>58</b>.

0061The shell <b>58</b> is fastened on the lower face <b>32</b> of the lower floor <b>22</b>. The shell <b>58</b> is in the form of a cup open toward the lower face <b>32</b> of the lower floor <b>22</b>. The shell <b>58</b> includes a bottom partition <b>60</b>, an upper partition <b>61</b> formed by the lower floor <b>22</b>, and a side partition <b>64</b>. The bottom partition <b>60</b> and the side partition <b>64</b> are formed by the shell <b>58</b>. The bottom partition <b>60</b> extends substantially parallel to and away from the upper partition <b>61</b> formed by the lower floor <b>24</b>. The shell <b>58</b> further comprises an outer collar <b>66</b> that radially extends the side partition <b>64</b> toward the outside of the shell <b>58</b>. The outer collar <b>66</b> extends in a direction parallel to the bottom partition <b>60</b>.

0062The collar is rigidly fastened to the lower floor <b>22</b>. It is fastened to the lower floor <b>22</b> by means of one or more removable mechanical fastening part(s) <b>74</b>, for example by means of a screw-nut assembly <b>74</b> and optionally a seal <b>76</b>, as shown in <figref idref="DRAWINGS">FIG. 3</figref>.

0063In an alternative of the second embodiment (not shown), the cavity <b>26</b> is formed by the upper floor <b>24</b> and the shell <b>58</b>.