Sill assembly for a motor vehicle equipped with a battery pack mounted under its front floor

Abstract

The invention relates to a rocker panel assembly comprising: - a sheet metal subframe including a front floor (110) and at least one front crossmember (160) fixed to the top of said floor; - a battery pack (200) located under said floor and provided with a hollow casing (210) comprising a roof wall (211) and a bottom wall (212); - first and second means for fixing said battery pack to said subframe, these second means of fixing comprising at least one sheet metal support bracket (410) interposed between said floor and said crossmember (160), to which it is fixed by triple-thickness electric welds, and, for each bracket, at least one fastening screw (420) passing through it and said battery pack, the threaded distal end of which (421) is bolted to a nut (415). Figure to be published with the abbreviation: Fig. 4

Description

Title of the invention: Underbody assembly for a motor vehicle equipped with a battery pack fixed under its front floor Technical field

[0001] The present invention relates to electrically powered motor vehicles equipped with a propulsion battery pack. It relates in particular to a rocker panel assembly for such a motor vehicle comprising a body underbody and a battery pack fixed under this front floor. Prior art

[0002] The propulsion battery of an electrically powered motor vehicle comprises at least one battery module comprising several electrochemical cells capable of generating current by chemical reaction (these cells may, for example, be of the Li-ion type, of the Ni-Mh type, or even Ni-Cd).

[0003] When such a battery comprises several modules, they are grouped in a casing to form a battery block more commonly referred to by the English expression "battery pack" and also containing a mounting interface, electrical and fluid connection connectors, as well as electrical or electronic means for managing the electrical energy of these modules.

[0004] Such a battery pack may be arranged inside the motor vehicle by covering the front floor of the sheet metal underbody of the vehicle, extending longitudinally between the front apron and the rear floor, and transversely between two side members.

[0005] However, such an installation has the main disadvantage of significantly reducing the habitability of the vehicle.

[0006] In order to remedy this problem, it is also known to install the battery pack under the front floor of the vehicle's underbody.

[0007] In order to ensure that such a battery pack is held in place on the underbody of the vehicle, it is known to use mounting crosspieces placed against the outer face of the bottom wall of the casing of this battery pack, extending transversely over the entire width of this casing, and the two ends of which are fixed to the two side rails bordering the front floor.

[0008] However, due to the very significant mass of this battery pack (which is also often concentrated on its central part) but also the vibrations generated during driving phases of the vehicle, a sagging of the central zone of the bottom wall of the casing can occur and generate significant forces on the two side members which then tend to deform or even tear.

[0009] In order to ensure better quality of fixing of such a battery pack, document KR 10-1209935 B1 proposes fixing against the inner face of the front floor several sheet metal support bridges, extending transversely under a longitudinal tunnel formed by stamping in the middle part of this front floor, and against which the outer face of the upper wall of the battery pack is intended to rest.

[0010] This document also provides several attachment screws successively passing through a support bridge, the battery pack and a lower support plate intended to rest against the outer face of the lower wall of this battery pack.

[0011] The threaded distal ends of these screws protruding from this lower support plate are further bolted to nuts so that the battery pack is sandwiched.

[0012] Such a solution proves to be particularly effective in preventing sagging of the central area of ​​the bottom wall of the battery pack housing.

[0013] However, it is not applicable to vehicles whose underbody does not have such a longitudinal tunnel.

[0014] Furthermore, given the significant forces undergone by these bridges, it may happen that the latter become detached from the front floor and thus no longer ensure the retention of the central zone of the bottom wall of the battery pack housing. Statement of the invention

[0015] The present invention therefore aims to improve the situation.

[0016] For this purpose, it proposes a set of underbody panels for a motor vehicle comprising: - a sheet metal underbody comprising a front floor extending transversely between two side members and at least one front seat cross member fixed on top of said front floor; - a battery pack installed under said front floor between said side members, said battery pack being provided with a hollow casing comprising a roof wall, a bottom wall and a peripheral strip together defining an internal volume containing several battery modules; - first means for fixing said battery pack to said body underbody; and - second means for fixing said battery pack to said body underbody comprising at least one sheet metal support bridge fixed to said front floor and, for each said bridge, at least one attachment screw passing through it and said battery pack and the threaded distal end of which is bolted onto a nut so as to ensure the vertical retention of a portion of this battery pack; characterized in that each said at least one support bridge is interposed between said front floor and a said cross member to which it is fixed by triple-thickness electric welding points of sheet metal.

[0017] These second fixing means thus have the advantage of being able to be implemented on vehicles whose underbody does not have such a longitudinal tunnel.

[0018] Furthermore, the invention ensures better mechanical strength of the support bridge(s) thanks to their attachment to the front floor by triple-thickness electric welding points of sheet metal. The invention thus makes it possible to avoid (or at least considerably limit) any risk of tearing or sagging of a portion of the battery pack.

[0019] According to preferred characteristics of said set of underbody panels according to the invention: - each said support bridge comprises a sole resting on a portion of said front floor located directly above the top wall of said crossmember, as well as two attachment grooves extending this sole longitudinally and each sandwiched between said front floor and a corresponding attachment groove of said crossmember, these three superimposed elements being fixed by said electric welding points with triple thickness of sheet metal; - the sole of each said bridge is raised with respect to its attachment grooves by means of two grooves made at the level of the junctions between this sole and these attachment grooves; - each said attachment screw, introduced from below said battery pack, successively passes through said battery pack via two corresponding inlet and intermediate orifices provided respectively in the bottom wall and the roof wall of said casing, said front floor and a said corresponding bridge via an outlet orifice provided in the latter, its threaded distal end projecting from this bridge being bolted onto a said nut welded to the upper periphery of this outlet orifice while its head cooperates in abutment against the lower periphery of this inlet orifice; - the bottom wall of said casing has, at the level of each said inlet orifice provided in the latter, a respective recess housing the head of a corresponding attachment screw; - said second fixing means also comprise, for each said attachment screw, a shim washer interposed between said front floor and the roof wall of said casing, being crossed by this screw so as to be compressed between this front floor and this roof wall after its bolting; - each said shim washer is made of an elastomer material; - said second fixing means comprise at least one pair of two said support bridges arranged symmetrically on either side of the median vertical longitudinal plane of said front floor; and / or - said first fixing means comprise two lateral fins projecting transversely on the external side from the two lateral portions of the peripheral strip of said casing, each said lateral fin having several orifices provided at regular intervals along its length and being crossed by screws introduced from below this fin and also passing through corresponding holes provided in a said corresponding lateral side member of the body underbody before being screwed onto nuts welded on the upper periphery of these holes.

[0020] The invention also relates, in a second aspect, to a motor vehicle comprising such a set of underbody panels. Brief description of the drawings

[0021] The description of the invention will now be continued by the detailed description of an exemplary embodiment, given below for illustrative but non-limiting purposes, with reference to the appended drawings, in which: - [Fig.l] represents a perspective view from above of a set of underbody panels of a motor vehicle according to the invention with electric drive equipped with a front floor under which a battery pack is installed; - [Fig.2] is an enlargement of detail II of [Fig.l] showing the second means of fixing this battery pack by transparency through the rear cross member of the front seat; - [Fig.3] represents a perspective view from below of the underbody assembly of [Fig.l]; and - [Fig.4] is a perspective sectional view taken along a vertical longitudinal sectional plane passing through one of the fixing screws included in these second fixing means. Description of the embodiments

[0022] [Fig.l] represents a perspective view from above of a set of underbody panels according to the invention 1 of a motor vehicle comprising an electric propulsion machine.

[0023] We define with respect to this set of rocker panels 1 an orthogonal reference XYZ comprising three axes perpendicular two by two, namely: - an X axis, defining a longitudinal, horizontal direction, parallel to the ground and coincident with the general direction of movement of the vehicle - a Y axis, defining a transverse, horizontal direction, also parallel to the ground and which with the X axis defines a horizontal XY plane, and - a Z axis, defining a vertical direction, perpendicular to the ground as well as to the plane XY horizontal.

[0024] In the remainder of the description and with reference to the reference defined above, the terms “longitudinal” or “longitudinally” will refer to a direction parallel to the X axis, the terms “transverse” or “transversely” will refer to a direction parallel to the Y axis, and the terms “vertical” or “vertically” will refer to a direction parallel to the Z axis.

[0025] On the other hand and by convention, the terms "lower", "upper", "front" and "rear" will be understood in relation to the general orientation of the vehicle. The terms "lower" and "low" will indicate a greater proximity to the ground in the vertical direction than the terms "upper" or "high". The term "front" will indicate a positioning oriented towards the front of a vehicle in the horizontal direction and the term "rear" will indicate a positioning oriented towards the rear of a vehicle in the same horizontal direction.

[0026] The terms "external" and "internal" will be used to define the relative position of an element with reference to the median vertical longitudinal plane of the vehicle. The element closest to this plane will thus be described as internal as opposed to the other element further from this same plane which will be described as external.

[0027] With reference to this [Fig.l], the underbody assembly 1 comprises a sheet metal underbody 100, comprising a front floor 110 extending longitudinally between the front apron 120 and the rear floor 130 intended to support the rear seats (also called “row 2 seats”), and transversely between two lateral side members 140.

[0028] This body underbody 100 also comprises a front seat cross member 150 and a front seat rear cross member 160 fixed on top of the front floor 110 and extending transversely between the two side members 140 under the front row of seats.

[0029] These two front seat crosspieces 150, 160, on which the seat frames of these front seats are fixed, have a section that is substantially U-shaped, the concavity of which is turned towards the front floor 110.

[0030] As illustrated in [Fig.2], each cross member 150, 160 comprises a substantially horizontal top wall 151, 161 surmounting the front floor 110, as well as two wings 152, 162 extending substantially vertically to this floor 110 from and along the two lateral edges of this top wall 151, 161. These two wings 152, 162 each extend opposite the top wall 151, 161 by two horizontal attachment rabbets 153, 163 which are welded to said floor 110 by electric welding points (EPS).

[0031] With reference to [Fig.3], the underbody assembly 1 also comprises a block- battery 200 extending along a substantially horizontal average plane and located under the front floor 110 of the underbody 100 between the side rails 140.

[0032] This battery pack 200 is provided with a hollow casing 210 comprising a substantially horizontal roof wall 211 arranged opposite the front floor 110, a substantially horizontal bottom wall 212, and a peripheral strip 213 together defining an internal volume containing several battery modules 220 (see [Fig.4]) each comprising several electrochemical cells capable of generating current by chemical reaction.

[0033] This casing 210 can also house other elements not shown, such as a mounting interface, electrical and fluid connection connectors, and / or electrical or electronic means for managing the electrical energy of these modules.

[0034] As illustrated by [Fig.3] and in order to partially ensure the fixing of the battery pack 200 against the front floor 110 of the vehicle, the underbody assembly 1 comprises first fixing means 300 comprising two lateral fins 310, substantially horizontal, projecting transversely on the external side from the two lateral portions of the peripheral strip 213.

[0035] Each lateral fin 310 has several orifices arranged at regular intervals along its length and being crossed by screws 320 introduced from below this fin 310 and also passing through corresponding holes (not visible) arranged in a corresponding lateral side member 140 of the body underbody 100 before being screwed onto nuts welded on the upper periphery of these holes and not visible in the figures.

[0036] According to the invention and in order to ensure better quality of fixing of the battery pack 200 to the front floor 110 while avoiding any risk of sagging of a portion of the bottom wall 212 of the casing 210, the underbody assembly 1 also comprises second fixing means 400.

[0037] As illustrated by figures 2 and 4, these second fixing means 400 comprise at least one sheet metal support bridge 410 extending in a longitudinal direction while being interposed vertically between the front floor 110 and the front seat rear cross member 160 to which it is fixed.

[0038] Advantageously and as illustrated by [Fig.2], the second fixing means 400 comprise at least one pair of two support bridges 410 arranged symmetrically on either side of the median vertical longitudinal plane of the front floor 110.

[0039] With reference to [Fig.4], each support bridge 410 comprises a sole 411 resting substantially horizontally on a boss 111 formed in the front floor 110 opposite the top wall 161 of the cross member 160.

[0040] Each support bridge 410 also comprises two attachment grooves 412 extending longitudinally this sole 171 and each sandwiched between this front floor 110 and a corresponding attachment groove 163 of this cross member 160, these three superimposed elements 110, 412, 163 being fixed by electric welding points (EWS).

[0041] Each resulting from the localized fusion of the three sheets forming respectively the front floor 110, a support bridge 410 and the cross member 160, these electric welding points with triple sheet thickness thus ensure excellent mechanical strength of each support bridge 410 to the front floor 110.

[0042] In order to compensate for the slight vertical gap between the boss 111 on which the sole 411 rests and the periphery of this boss 111 against which the attachment grooves 412 rest, each support bridge 410 is provided with two grooves 413 made at the junctions between this sole 411 and these attachment grooves 412.

[0043] It is recalled that a jog constitutes a recess made on a sheet metal part by its shaping by folding or stamping according to a flattened S-shaped profile so as to separate by a predefined distance the average plane of a part of this part from the average plane of the rest of this part.

[0044] The sole 411 of each bridge 410 is provided with at least one circular outlet orifice 414 overlapping with a complementary orifice 112 provided in the front floor 111, a nut 415 being further welded to this sole 411 on the upper periphery of each outlet orifice 414.

[0045] The complementary fixing means also comprise, for each bridge 410, at least one attachment screw 420 introduced from below the battery pack 200 and successively passing, in a vertical direction, this battery pack 200 (via two inlet orifices 212A and intermediate orifices 211A provided respectively in the bottom wall 212 and the roof wall 211 of the casing 210), the front floor 111 as well as the sole 411 of this bridge 410 (via an outlet orifice 414). The threaded distal end 421 of this screw 420 projecting from this bridge 410 is further bolted onto a nut 415 welded to the upper periphery of this outlet orifice 414.

[0046] After bolting and as illustrated by [Fig. 4], the head 422 of each attachment screw 420 cooperates in abutment against the lower periphery of the corresponding inlet orifice 212A of the bottom wall 212 of the casing 210, so as to ensure the vertical retention of a portion of this battery pack 200 and to avoid any risk of the latter collapsing.

[0047] In order to reduce vibrations and noise build-up in the passenger compartment during driving phases, the second fixing means 400 may also advantageously comprise, for each said screw 420, a shim washer 430 interposed between the front floor 110 and the roof wall 211, being crossed by this screw 420 so as to be compressed between this front floor 110 and this roof wall 211 after its bolting.

[0048] Each shim washer 430 is preferably made of an elastomeric material (for example, natural rubber or EPDM).

[0049] Furthermore, and in order to prevent the attachment screw heads 420 from protruding below the battery pack 200 where they could constitute attachment elements for objects present on the roadway such as branches, the bottom wall 212 of the casing 210 has, at the level of each passage orifice 212A formed in the latter, a respective recess 212B housing the head of a corresponding attachment screw 420.

[0050] Numerous variants are conceivable and it is recalled in this regard that the present invention is not limited to the embodiments described and shown, but also encompasses all the variants of execution within the reach of those skilled in the art.

Claims

Claims

1. Underbody assembly (1) for a motor vehicle comprising: - a sheet metal underbody (100) comprising a front floor (110) extending transversely between two side members (140) and at least one front seat cross member (150, 160) fixed on top of said front floor (110); - a battery pack (200) located under said front floor (110) between said side members (140), said battery pack (200) being provided with a hollow casing (210) comprising a roof wall (211), a bottom wall (212) and a peripheral strip (213) together defining an internal volume containing several battery modules (220); - first means (300) for fixing said battery pack (200) to said underbody (100);and - second means (400) for fixing said battery pack (200) to said body underbody (100) comprising at least one sheet metal support bridge (410) fixed to said front floor (110) as well as, for each said bridge (410), at least one attachment screw (420) passing through it as well as said battery pack (200) and the threaded distal end (421) of which is bolted onto a nut (415) so as to ensure the vertical retention of a portion of this battery pack (200); characterized in that each said at least one support bridge (410) is interposed between said front floor (110) and a said crossmember (160) to which it is fixed by triple-thickness sheet metal electric welding points.;

2. Underbody assembly (1) according to claim 1, characterized in that each said support bridge (410) comprises a sole (411) resting on a portion of said front floor (411) located directly above the top wall (161) of said crossmember (160), as well as two attachment grooves (412) extending longitudinally this sole (411) and each sandwiched between said front floor (110) and a corresponding attachment groove (163) of said crossmember (160), these three superimposed elements (110, 412, 163) being fixed by said electric welding points with triple sheet thickness.

3. Set of rocker panels (1) according to claim 2, characterized in that the sole (411) of each said bridge (410) is raised with respect to its attachment grooves (412) by means of two grooves (413) made at the junctions between this sole (411) and these fastener rebates (412).

4. Underbody assembly (1) according to one of claims 1 to 3, characterized in that each said attachment screw (420), introduced from below said battery pack (200), successively passes through said battery pack (200) via two corresponding inlet (212A) and intermediate (211A) orifices provided respectively in the bottom wall (212) and the roof wall (211) of said casing (210), said front floor (110) and a said corresponding bridge (410) via an outlet orifice (414) provided in the latter, its threaded distal end (421) projecting from this bridge (410) being bolted onto a said nut (415) welded to the upper periphery of this outlet orifice (414) while its head (422) cooperates in abutment against the lower periphery of this inlet orifice (414).

5. Underbody assembly (1) according to claim 4, characterized in that the bottom wall (212) of said casing (210) has, at the level of each said inlet orifice (212A) formed in the latter, a respective recess (212B) housing the head (422) of a corresponding attachment screw (420).

6. Underbody assembly (1) according to one of claims 1 to 5, characterized in that said second fixing means (400) also comprise, for each said attachment screw (420), a shim washer (430) interposed between said front floor (110) and the roof wall (211) of said casing (210) and being crossed by this screw (420) so as to be compressed between this front floor (110) and this roof wall (211) after its bolting.

7. Underbody assembly (1) according to claim 6, characterized in that each said shim washer (430) is made of an elastomeric material.

8. Underbody assembly (1) according to one of claims 1 to 7, characterized in that said second fixing means (400) comprise at least one pair of two said support bridges (410) arranged symmetrically on either side of the median vertical longitudinal plane of said front floor (410).

9. Underbody assembly (1) according to one of claims 1 to 8, characterized in that said first fixing means (300) comprise two lateral fins (310) projecting transversely on the external side from the two lateral portions of the peripheral strip (213) of said casing (210), each said lateral fin (310) having several orifices arranged at regular intervals along its length and being crossed by screws (320) introduced from below this fin (310) and also passing through corresponding holes made in a said corresponding lateral side member (140) of the body underbody (100) before being screwed onto nuts welded on the upper periphery of these holes.

10. Motor vehicle comprising a set of underbody panels (1) according to one of claims 1 to 9.

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