Underbody for an electric or hybrid motor vehicle and method for mounting such an underbody

Abstract

The invention relates to an underbody for an electric or hybrid motor vehicle, which underbody comprises: an upper floor (2) having an upper face (2a) and a lower face (2b) opposite the upper face (2a), one or more attachment members (5) configured to suspend battery modules (6), the attachment members (5) being attached by welding to the lower face (2a) of the upper floor (2); and a plurality of central crosspieces (4) positioned on the upper face (2a) of the upper floor (2), the central crosspieces (4) being attached to the upper face (2a) of the upper floor (2) by welding or the central crosspieces (4) forming a one-piece structure with the upper floor (2).

Description

[0001] TITLE: Base for electric or hybrid motor vehicle and method of mounting such a base

[0002] Technical field

[0003] The present invention relates, in general, to electric or hybrid vehicles and, in particular, to the sealing of an electrical energy storage zone intended to accommodate battery modules of such vehicles.

[0004] More specifically, the invention relates to a base for an electric or hybrid vehicle, to an electric or hybrid vehicle comprising such a base, as well as to a method of mounting such a base in an electric or hybrid vehicle.

[0005] Previous techniques

[0006] In current electric vehicles, electrical energy is stored in battery cells packaged in an external casing housed under the floor of the vehicle.

[0007] This housing is waterproof and ensures the function of storing and maintaining the cells in the vehicle, generally by including intermediate packaging called modules. It also contributes to the protection of the cells in frontal and side impacts.

[0008] However, such a case limits the volume useful for storing electrical energy.

[0009] According to a new design, the external housing present under the floor is removed in order to maximize the available volume of the electrical energy storage area intended to receive the battery cells. The underbody is reconfigured and itself forms a structural enclosure for receiving the battery cells.

[0010] The battery modules are positioned under the upper floor.

[0011] Certain sealing requirements are imposed on the electrical energy storage area. It must be temperature and pressure-tight with respect to the passenger compartment in order to resist potential thermal runaway of the battery cells and protect the passengers in the vehicle.

[0012] In particular, the GTR-EVS (Global Technical Regulations - Electric Vehicle Safety) regulations require that fumes must not enter the passenger compartment for a minimum of five minutes, in order, in particular, to give passengers time to get out of the vehicle.

[0013] The removal of the casing results in the removal of the sealing of the electrical energy storage area intended to accommodate the battery modules.

[0014] Statement of the invention

[0015] The invention therefore aims to remedy these drawbacks and to propose a base and a mounting method making it possible to maintain the seal between the passenger compartment of an electric or hybrid vehicle and the electrical energy storage area arranged under the upper floor and intended to receive battery modules.

[0016] There is therefore proposed a base for an electric or hybrid motor vehicle, comprising: an upper floor comprising an upper face and a lower face opposite the upper face, one or more fixing members configured to suspend battery modules, the fixing members being fixed by welding to the lower face of the upper floor; and a plurality of central cross members positioned on the upper face of the upper floor, the central cross members being fixed to the upper face of the floor by welding or the central cross members forming a single-piece structure with the upper floor.

[0017] Preferably, the base comprises an electrical energy storage area intended to receive battery modules, the electrical energy storage area being delimited by the upper floor and a lower closing plate.

[0018] Advantageously, the base may comprise at least one first sealing means arranged between the upper floor and the lower closing plate.

[0019] In one embodiment, the upper floor may comprise a central platform and a perimeter extending respectively in two distinct planes to form a hollow body capable of receiving battery modules, the perimeter comprising a first zone extending continuously on said upper face and a second zone extending continuously on said lower face.

[0020] Preferably, the first sealing means is arranged between the second area of ​​the perimeter of the upper floor and the lower closing plate.

[0021] The invention also relates to a motor vehicle comprising a base as described above. The invention also relates to a method for mounting a base as described above in an electric or hybrid motor vehicle, the mounting method comprising the following steps: optionally, fixing by welding the central cross members to the upper face of the upper floor when the central cross members and the upper floor do not form a single-piece structure; fixing by welding to the lower face of the upper floor the fixing members configured to suspend battery modules; and fixing the upper floor to the motor vehicle by screwing the central cross members, in particular onto additional cross members of the base.

[0022] According to one embodiment, the assembly method may comprise, after fixing the upper floor to the motor vehicle, fixing the battery modules to the fixing members (5), in particular by screwing.

[0023] According to one characteristic, the assembly method may comprise, after fixing the battery modules to the fixing members (5), the following successive steps: the installation of a first sealing means; and the fixing, in particular by screwing, of a lower closing plate delimiting with the upper floor an electrical energy storage zone intended to receive the battery modules, the first sealing means being arranged between the upper floor and the lower closing plate.

[0024] According to another embodiment, the assembly method may comprise, before fixing the upper floor to the motor vehicle, fixing the battery modules to the fixing members, in particular by screwing.

[0025] According to another characteristic, the assembly method may comprise, after fixing the battery modules to the fixing members, and before fixing the upper floor to the motor vehicle, the following successive steps: the installation of a first sealing means; and the fixing, in particular by screwing, of a lower closing plate delimiting with the upper floor an electrical energy storage zone intended to receive the battery modules, the first sealing means being arranged between the upper floor and the lower closing plate.

[0026] Brief description of the drawings Other aims, advantages and characteristics will emerge from the description which follows, given purely for illustrative purposes and with reference to the attached drawings in which:

[0027] [Fig 1] illustrates a base for an electric or hybrid motor vehicle according to an embodiment of the invention shown in longitudinal section.

[0028] [Fig 2] is a cross-section of the base shown in Figure 1. [Fig 3] is a detailed perspective view of a battery module suspended from two mounting members of the base shown in Figure 1.

[0029] [Fig 4] is a detailed bottom view of battery modules suspended from the underbody mountings shown in Figure 1.

[0030] [Fig 5] is a longitudinal sectional view of an upper floor of the base shown in Figure 1.

[0031] [Fig 6] is a cross-sectional view of an upper floor of the basement shown in Figure 1.

[0032] [Fig 7] is a flowchart illustrating a method of mounting a base for an electric or hybrid motor vehicle according to an embodiment of the invention.

[0033] [Fig 8] is a flowchart illustrating a method of mounting a base for an electric or hybrid motor vehicle according to another embodiment of the invention.

[0034] Detailed description

[0035] In the remainder of the description, the terms "longitudinal", "transverse", "vertical", "horizontal", "front", "rear", "left", "right", "lower", "upper", "under", "on", "above" and "below" are understood in relation to the usual orthogonal reference frame for motor vehicles, shown in Figures 1 to 6, and comprising:

[0036] - a longitudinal axis X, horizontal and directed from the front to the rear of the vehicle;

[0037] - a transverse axis Y, horizontal, perpendicular to the X axis and directed from the left to the right of the vehicle moving forward;

[0038] - a Z axis, orthogonal to the X and Y axes and vertically directed from bottom to top.

[0039] Furthermore, the expression "at least one" used in this description is equivalent to the expression "one or more".

[0040] Figures 1 and 2 illustrate a base 1 for an electric or hybrid motor vehicle in section along, respectively, the longitudinal axis X and the transverse axis Y.

[0041] The base 1 comprises an upper floor 2 comprising an upper face 2a and a lower face 2b opposite the upper face 2a. Advantageously, the base 1 may also comprise a central frame positioned on the periphery of the upper floor 2 and comprising a front cross member 7, a rear cross member 8 and left and right side flaps 3.

[0042] By sill, we mean in the present invention a structural element which extends in the longitudinal direction of the vehicle on each side of the upper floor 2, in particular below the doors of the vehicle.

[0043] Only a lateral portion of the base 1 is shown in figure 2 so that only the left side flap 3 of the central frame is visible.

[0044] Preferably, a plurality of central crosspieces 4 are fixed to the upper face 2a of the upper floor 2.

[0045] Preferably, the ends of the central crosspieces 4 are connected by embedding to the left and right side flaps 3. The central crosspieces 4 may be provided in sufficient number to cover the entire length of the upper floor 2 and thus to compensate for lateral impacts regardless of their position.

[0046] Advantageously, the central cross members 4 may include cross members for reinforcing the upper floor 2 in the event of a side impact and fixing cross members intended for fixing seats of the motor vehicle.

[0047] An electrical energy storage area ZE intended to receive battery modules is advantageously provided under the upper floor 2.

[0048] The upper floor 2 forms a sealing barrier between the electrical energy storage area ZE and the passenger compartment of the vehicle.

[0049] In the example illustrated, the central crosspieces 4 are fixed to the upper face 2a of the upper floor 2 by welding, that is to say by means of welding points or beads. This makes it possible to avoid removing the seal formed by the upper floor 2 piercing the electrical energy storage zone ZE.

[0050] According to an alternative embodiment, the central crosspieces 4 and the upper floor 2 can be in one piece so that the central crosspieces 4 are directly integrated into the upper floor 2 and the upper floor 2 integrates the dual function of floor and reinforcing crosspieces.

[0051] Fastening members 5 configured to suspend at least one battery module 6 under the upper floor 2 are housed in the electrical energy storage zone ZE.

[0052] By "suspending at least one battery module of the vehicle" is meant that the battery module 6 is supported in its upper part positioned opposite the upper floor 2 by the fixing member 5 so that the battery module 6 is suspended from the fixing member 5 without it being necessary for the battery module 6 to rest on a base. The fixing members 5 are fixed to the lower face 2b of the upper floor 2 by welding, that is to say by means of welding points or beads. This makes it possible to avoid removing the seal formed by the upper floor 2 piercing the electrical energy storage zone ZE.

[0053] In the example illustrated, each fixing member 5 comprises a beam extending longitudinally along a longitudinal axis of the upper floor 2 in the electrical energy storage zone ZE.

[0054] The beam of the fixing member 5 has, for example, a substantially omega-shaped cross-section whose free ends advantageously allow the fixing member 5 to be fixed to the lower face 2b of the upper floor 2.

[0055] The beam may be formed from a sheet, such as a stamped or profiled steel sheet.

[0056] The base advantageously comprises means F1 for fixing the battery modules 6 to the fixing members 5.

[0057] In this regard, the battery modules 6 may comprise at least one fixing lug 6a configured to cooperate with one of the fixing members 5 for suspension of the battery module 6 from the fixing member 5.

[0058] As shown in Figures 3 and 4, the illustrated battery modules 6 include a plurality of mounting tabs 6a.

[0059] In the example illustrated, the battery modules 6 are fixed to the fixing members 5 by screwing.

[0060] Advantageously, the means F1 for fixing the battery modules 6 to the fixing members 5 comprise, for example, a plurality of screw and nut assemblies.

[0061] Each fixing lug 6a may advantageously comprise a hole configured to cooperate with a hole formed in a section of the beam for screwing the battery modules 6 onto the fixing members 5.

[0062] In the example illustrated, the screwing of the fixing lugs 6a is carried out on a lower edge of the fixing members 5 positioned in a direction opposite to the upper floor 2.

[0063] Each battery module 6 comprises a first row of fixing lugs 6a and a second row of fixing lugs 6a extending along the longitudinal axis X of the vehicle, and positioned, respectively, on first and second opposite lateral faces of the battery module 6. The fixing lugs 6a of each of the first and second rows are arranged at regular intervals over the entire length of the battery module 6 in order to distribute the weight of the battery modules 6 along the entire length of the upper floor 2. Preferably, the fixing lugs 6a of two adjacent modules are arranged in a staggered pattern.

[0064] Advantageously, a lower closing plate 8 makes it possible to close the electrical energy storage zone ZE, ensuring the protection of the battery modules 6, in particular against road debris. The electrical energy storage zone ZE is thus delimited by the upper floor 2 and the lower closing plate 8 when the latter two are assembled.

[0065] The lower closing plate 9 is, advantageously, substantially flat.

[0066] The base 1 advantageously comprises means F2 for fixing the lower closing plate 8 to the upper floor 2.

[0067] The means F2 for fixing the lower closing plate 9 to the upper floor 2 comprise, for example, a plurality of screw and nut assemblies, for fixing the lower closing plate 9 to the upper floor 2 by screwing.

[0068] In the example illustrated, the upper floor 2 comprises a central platform 10 and a perimeter 11, connected by a side 12, extending respectively in two distinct planes to form a hollow body capable of receiving the battery modules 6. The hollow body formed by the upper floor 2 takes the form of a bell or even a bowl.

[0069] A plurality of orifices are provided on the periphery 11 of the upper floor 2, and each screw and nut assembly of the fixing means F2 cooperates with one of these orifices.

[0070] In the example illustrated, the central crosspieces 4 are welded onto the central platform 10.

[0071] Preferably, the dimensions of the upper floor 2 are adapted to receive, and in particular to surround, at least one battery module 6.

[0072] In the illustrated example, the height of the central platform 10 and the perimeter 11 is greater than the height of a battery module.

[0073] The longitudinal axis of each battery module 6 extends along the longitudinal axis X of the motor vehicle.

[0074] Preferably, the central platform 10 and the perimeter 11 are in one piece in order to form a first sealed protection for the electrical energy storage zone ZE.

[0075] The upper floor 2 preferably comprises a material having an elastic limit of a value greater than or equal to 400 mPa, preferably greater than or equal to 1000 mPa, such as steel, in order to give the upper floor 2 sufficient bending stiffness to withstand a lateral impact. Advantageously, a vertical clearance J1 remains between each battery module 6, fixed to the upper floor 2 by means of a fixing member 5, and the lower closing plate 9.

[0076] The bottom plate 9 comprises, for example, aluminum and / or a fiber-reinforced plastic material.

[0077] Preferably, each fixing member 5 comprises an electrically insulating material in order to electrically insulate the battery modules 6 from the upper floor 2.

[0078] Advantageously, a vertical gap J2 remains between each battery module 6 housed in the electrical energy storage zone ZE and the upper floor 2 in order to electrically isolate the battery module 6 from the upper floor 2.

[0079] Optionally, the base 1 may comprise an insulating foam (not shown), in particular for thermal protection, surrounding the battery modules 6 in the electrical energy storage zone ZE.

[0080] The perimeter 11 of the upper floor 2 comprises a first zone 11a, arranged on the upper face 2a, extending continuously.

[0081] The periphery 11 also comprises a second zone 11b, opposite the first zone 11a, arranged on the lower face 2b, and extending continuously.

[0082] By continuous zone is meant an area where the material of the upper floor 2 forms a continuity, without opening or orifice, extending all along the perimeter 1 1 so as to form a single closed track.

[0083] Preferably, a first sealing means is arranged between the upper floor 2 and the lower closing plate 9 in order to ensure the sealing of the electrical energy storage zone ZE.

[0084] In the example illustrated, the second zone 11b is intended to receive the first sealing means 13.

[0085] Preferably, a second sealing means is arranged between the central frame and the upper floor 2 in order to ensure the sealing of the passenger compartment of the vehicle with respect to the exterior of the vehicle.

[0086] In the example illustrated, the first zone 11a is intended to receive the second sealing means 14.

[0087] The first and second zones 11a and 11b are thus configured to each form a single sealing track, continuous along the entire perimeter 11 of the upper floor 2.

[0088] Preferably, the first and second sealing means 13 and 14 each comprise a seal. The seal of the first and second sealing means 13 and 14 may be made of mastic.

[0089] The first zone 11a forms, in addition to a sealing track for the second sealing means 14, an assembly and docking zone of the upper floor 2 on the central frame during the assembly of the various constituent parts of the base 1.

[0090] When the central frame and the upper floor 2 are assembled, the second sealing means 14 is gripped between the first zone 11a of the perimeter 11 of the upper floor 2 and the central frame.

[0091] Furthermore, when the upper floor 2 and the lower closing plate 9 are assembled, the first sealing means 13 is gripped between the second zone 11b of the perimeter 11 of the upper floor 2 and the perimeter of the lower closing plate 9.

[0092] In the example illustrated, the fixing means F2 of the lower closing plate 9 on the upper floor 2 also make it possible to fix the upper floor 2 on the central frame.

[0093] The holes provided on the periphery 11 of the upper floor 2 and the fixing means F2, which allow the upper floor 2 to be fixed to the central frame and to the lower closing plate 9, are arranged between the first and second sealing zones 11a and 11b.

[0094] The first sealing means 13, positioned between the second zone 11b of the perimeter 11 of the upper floor 2 and the perimeter of the lower closing plate 9, is arranged opposite the electrical energy storage zone ZE, at a distance from the fixing means F2 so that the drilling of the orifices intended for the fixing means F2 does not degrade the sealing thus formed of the electrical energy storage zone ZE with respect to the passenger compartment of the vehicle.

[0095] The second sealing means 14, positioned between the first zone 11a of the perimeter 11 of the upper floor 2 and the central frame, is arranged facing the exterior of the vehicle, at a distance from the fixing means F2 so that the drilling of the orifices intended for the fixing means F2 does not degrade the sealing thus formed of the passenger compartment of the vehicle with respect to the exterior of the vehicle.

[0096] Advantageously, the central platform 10 and the perimeter 11 extend in two substantially parallel planes.

[0097] In the example illustrated, the perimeter 11 of the upper floor 2, the face of the central frame intended for docking with the perimeter 11 of the upper floor 2 and the perimeter of the lower closing plate 9 are substantially flat.

[0098] The various means of sealing the electrical energy storage zone allowing sealing of the electrical energy storage zone ZE with respect to the interior of the passenger compartment of the vehicle and vice versa are advantageously carried by a single part formed by the upper floor 2.

[0099] In addition, the perimeter 11 of the upper floor 2 forms a multifunctional zone making it possible to form sealing tracks as well as the docking of the upper floor 2 on the rest of the base 1.

[0100] Furthermore, the electrical energy storage area ZE may comprise a space 15, which may for example be delimited by a box, for the storage of electrotechnical elements such as electrical cables, or a device for cooling the battery modules 6.

[0101] Upper floor 2 can be manufactured by stamping.

[0102] With reference to figure 5, the central crosspieces 4 are fixed by fixing means F3 on additional crosspieces 16 of the base 1.

[0103] In the illustrated example, the central crosspieces 4 are fixed by screwing. The means F3 for fixing the central crosspieces 4 to additional crosspieces 16 comprise, for example, a plurality of screw and nut assemblies.

[0104] As illustrated in Figure 6, the base 1 comprises a plurality of local reinforcing elements 17 intended to reinforce the mechanical resistance of the zones of the fixing members 5 crossed by the fixing means F1 of the battery modules 6.

[0105] Each local reinforcement 17 of a fixing member 5 is positioned locally between the nut of the fixing means F1 and the fixing member 5.

[0106] Advantageously, the local reinforcements 17 comprise a sheet, such as a steel sheet, substantially U-shaped so as to at least partially match the shape of the beam of the omega-shaped fixing member 5.

[0107] The invention also relates to a method of mounting the underbody 1 on a motor vehicle.

[0108] Figure 7 illustrates a first mode of implementation of the method for mounting the base 1.

[0109] In the example illustrated, the central crosspieces 4 and the upper floor 2 do not form a single-piece structure so that the assembly method comprises, firstly, the fixing 100 by welding of the central crosspieces 4 on the upper face 2a of the upper floor 2.

[0110] The method of mounting the base 1 illustrated then comprises the fixing 1 10 by welding the fixing members 5 on the lower face 2b of the upper floor 2.

[0111] According to an alternative embodiment, the step 110 of fixing the fixing members 5 can be carried out before or simultaneously with the fixing 100 of the central crosspieces 4 on the upper floor 2. By a fixing step 120, the battery modules 6 are then screwed onto the fixing members 5.

[0112] According to a variant, the battery modules 6 can be fixed to the fixing members 5 by a fixing method other than screwing.

[0113] Electrotechnical elements can also be mounted in the space 15 of the electrical energy storage area ZE.

[0114] Advantageously, the battery modules 6 and the electrotechnical elements can be mounted from outside the motor vehicle.

[0115] Preferably, the energy storage area ZE is then closed by the lower closing plate 9.

[0116] In this regard, a step 130 of installing a first sealing means 13 is carried out on the periphery of the lower closing plate 9 or on the second zone 11b of the periphery 11 of the upper floor 2.

[0117] Preferably, the first sealing means 13 installed is a sealing gasket.

[0118] The step 130 of installing the first sealing means 13 is followed by the fixing 140 by screwing the lower closing plate 9 onto the upper floor 2. The first sealing means 13 is then held in a vice between the second zone 11b of the perimeter 11 of the upper floor 2 and the perimeter of the lower closing plate 9.

[0119] Preferably, a step 150 of installing the second sealing means 14 is carried out on the central frame or on the first zone 11a of the perimeter 11 of the upper floor 2.

[0120] The upper floor 2 is then mounted on the motor vehicle, in particular on the rest of the underbody 1 by a step 160 of fixing by screwing the central crosspieces 4.

[0121] In the example illustrated, the central crosspieces 4 are fixed to the additional crosspieces 16 of the base 1.

[0122] Advantageously, the fixing 160 of the upper floor 2 can be carried out from inside the passenger compartment.

[0123] Figure 8 illustrates a second mode of implementation of the method of mounting the underbody 1 in which the battery modules 6 are only mounted under the upper floor 2 after mounting the upper floor 2 on the motor vehicle.

[0124] Firstly, and in a manner similar to the first embodiment, the assembly method advantageously comprises a step 200 of fixing by welding the central crosspieces 4 to the upper face 2a of the upper floor 2, then a step 210 of fixing by welding the fixing members 5 to the lower face 2b of the upper floor 2. According to an alternative embodiment, the step 210 of fixing the fixing members 5 can be carried out before or simultaneously with the fixing 200 of the central crosspieces 4 to the upper floor 2.

[0125] Preferably, a step 250 of installing the second sealing means 14 is carried out on the central frame or on the first zone 11a of the perimeter 11 of the upper floor 2.

[0126] The upper floor 2 is therefore mounted on the motor vehicle, by a step 260 of fixing by screwing the central crosspieces 4.

[0127] In the example illustrated, the central crosspieces 4 are fixed to the additional crosspieces 16 of the base 1.

[0128] The second sealing means 14 is then held in a vice between the central frame and the first zone 11a of the perimeter 11 of the upper floor 2.

[0129] The battery modules 6 are then screwed by a fixing step 220 onto the fixing members 5.

[0130] According to a variant, the battery modules 6 can be fixed to the fixing members 5 by a fixing method other than screwing.

[0131] The electrotechnical elements can also be mounted in the space 15 of the electrical energy storage area ZE.

[0132] In order to close the energy storage zone ZE, and in a similar manner to the first embodiment, a step 230 of installing the first sealing means 13 is preferably carried out on the periphery of the lower closing plate 9 or on the second zone 11b of the periphery 11 of the upper floor 2.

[0133] Preferably, the first sealing means 13 installed is a sealing gasket.

[0134] The step 230 of installing the first sealing means 13 is followed by the fixing 240 by screwing the lower closing plate 9 onto the upper floor 2. The first sealing means 13 is then held in a vice between the second zone 11b of the perimeter 11 of the upper floor 2 and the perimeter of the lower closing plate 9.

Claims

CLAIMS 1. Underbody for an electric or hybrid motor vehicle, comprising: an upper floor (2) having an upper face (2a) and a lower face (2b) opposite the upper face (2a), one or more fixing members (5) configured to suspend battery modules (6), the fixing members (5) being fixed by welding to the lower face (2a) of the upper floor (2); and a plurality of central cross members (4) positioned on the upper face (2a) of the upper floor (2), the central cross members (4) being fixed to the upper face (2a) of the upper floor (2) by welding or the central cross members (4) forming a single-piece structure with the upper floor (2).

2. Base according to claim 1, comprising an electrical energy storage area (ZE) intended to receive battery modules (6), the electrical energy storage area (ZE) being delimited by the upper floor (2) and a lower closing plate (9).

3. Base according to claim 2, comprising at least one first sealing means (13) arranged between the upper floor (2) and the lower closing plate (9).

4. Base according to any one of the preceding claims, in which the upper floor (2) comprises a central platform (10) and a periphery (11) extending respectively in two distinct planes to form a hollow body capable of receiving battery modules (6), the periphery (11) comprising a first zone (11a) extending continuously on said upper face (2a) and a second zone (11b) extending continuously on said lower face (2b).

5. Base according to claims 3 and 4, in which the first sealing means (13) is arranged between the second zone (Hb) of the periphery of the upper floor (2) and the lower closing plate (9).

6. Electric or hybrid motor vehicle comprising a base (1) according to any one of the preceding claims.

7. Method for mounting a base (1) according to any one of claims 1 to 5 in an electric or hybrid motor vehicle, comprising the following steps: optionally, fixing (100; 200) by welding the central crosspieces (4) on the upper face (2a) of the upper floor (2) when the central crosspieces (4) and the upper floor (2) do not form a single-piece structure; the fixing (1 10; 210) by welding on the lower face (2b) of the upper floor (2) of the fixing members (5) configured to suspend battery modules (6); and the fixing (160; 260) of the upper floor (2) on the motor vehicle by screwing the central crosspieces (4), in particular on additional crosspieces (16) of the underbody (1).

8. Method according to claim 7, comprising, after fixing (260) the upper floor (2) on the motor vehicle, fixing (220) the battery modules (6) on the fixing members (5), in particular by screwing.

9. Method according to claim 7, comprising, before fixing (160) the upper floor (2) on the motor vehicle, fixing (120) the battery modules (6) on the fixing members (5), in particular by screwing.

10. Method according to claim 8, comprising, after the fixing (120) of the battery modules (6) on the fixing members (5), the following successive steps: the installation (230) of a first sealing means (13); and the fixing (240), in particular by screwing, of a lower closing plate (9) delimiting with the upper floor (2) an electrical energy storage zone (ZE) intended to receive the battery modules (6), the first sealing means (13) being arranged between the upper floor (2) and the lower closing plate (9). 1 1. Method according to claim 9, comprising, after fixing (120) the battery modules (6) on the fixing members (5), and before fixing (160) the upper floor (2) on the motor vehicle, the following successive steps: the installation (130) of a first sealing means (13); and the fixing (140), in particular by screwing, of a lower closing plate (9) delimiting with the upper floor (2) an electrical energy storage zone (ZE) intended to receive the battery modules (6), the first sealing means (13) being arranged between the upper floor (2) and the lower closing plate (9).

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