VEHICLE TRACTION BATTERY WITH CROSS BEAMS SEPARATE MODULES WITH FIREPROOFING

Abstract

Electric or hybrid vehicle traction battery forming a flat casing comprising a lower tray (2) closed by a lid, inside crossbeams (8) each separating two adjacent zones receiving electrochemical cell modules (6), at the level of these crossbeams (8) free spaces connecting two adjacent zones, and comprising a foam strip fitted in each free space, which constitutes, at the level of these crossbeams (8), fire barriers between the two adjacent zones. Figure 4

Description

Title of the invention: VEHICLE TRACTION BATTERY COMPRISING CROSS BEAMS SEPARATE MODULES WITH FIREPROOFING

[0001] The present invention relates to an electric or hybrid vehicle traction battery comprising a flat casing having stiffening cross members separating receiving areas of modules containing electrochemical cells, with fire-resistant foams, as well as an electric or hybrid vehicle equipped with such a battery.

[0002] A known type of electric vehicle traction battery, presented in particular by document JP-A-2017196958, comprises a flat box fixed under the floor of the vehicle passenger compartment between the side rails of the body, including a lower tray and a cover.

[0003] The tray and the lid each comprise a set of internal stiffening cross members arranged along the transverse direction of the vehicle, these sets overlapping, the cross members delimiting areas receiving electrochemical cell modules.

[0004] The cell modules have horizontal fixing tabs on the sides inserted between the lower and upper cross members at the level of screws connecting these cross members, in order to achieve both a retention of these modules and a connection between the cross members which strongly stiffens the box.

[0005] Another type of known electric vehicle traction battery, presented in particular by document GB-A-2612805, has horizontal mounting tabs on the side of the modules for fixing to the cross members, which along these cross members alternate between the two modules arranged on each side in order to distribute the fixings of the modules close together along this cross member.

[0006] In general, it is known at the level of the stiffening crossbeams of the box, to make the connections between the lower tray and the cover stiffening the box and fixing the lateral tabs of the cell modules, which leave free passages between the two module reception areas separated by each crossbeam.

[0007] In particular, a known type of battery has upper crossbars fixed under the cover, each of which is connected to the lower tray by spaced screws fixed to this tray, and at the level of these crossbars screws for clamping the modules to the tray which leave under the crossbars a free passage space between the two lateral areas.

[0008] In the event of a problem with cells in a module causing significant heating and gas release, propagation possibilities are then obtained. These gases can escape to an adjacent module through the gaps in the crossmember separating them. This creates a risk of fire spreading from a faulty module to a neighboring one, worsening the accident, and then, through further spread, a risk of the entire battery igniting, making it even more difficult for firefighters to extinguish.

[0009] The present invention aims in particular to avoid these problems of the prior art.

[0010] To this end, it proposes a traction battery for an electric or hybrid vehicle forming a flat box comprising a lower tray closed by a lid, inside the crossbeams each separating two adjacent zones receiving electrochemical cell modules, and comprising at the level of these crossbeams free spaces connecting two adjacent zones, this battery being remarkable in that it comprises a strip of foam fitted in each free space, which constitutes at the level of these crossbeams fire barriers between the two adjacent zones.

[0011] One advantage of this battery is that, without modifying the battery itself, by simply fitting fire-resistant foam strips that fill the gaps left in the crossbeams, particularly towards the lower tray, and along the entire length of these crossbeams, a seal can be easily created between two adjacent module areas, preventing the spread of gas or fire from one to the other. In this way, the fire is confined to a single area of ​​the battery enclosure.

[0012] In addition, closing the passage between two module zones also prevents the diffusion of hot gas from one to the other, which in the event of overheating of cells on one side limits the heating of cells on the other side by ensuring better operation of the latter cells.

[0013] The electric vehicle traction battery according to the invention may further comprise one or more of the following characteristics, which may be combined with each other.

[0014] Advantageously, the modules include lateral fixing tabs which are fitted into cavities formed on the sides of the foam strips.

[0015] In this case, advantageously the cavities are open only in the direction of the module comprising the fixing tabs inserted inside, without opening out on the other side.

[0016] Advantageously, the foam strip comprises two superimposed plates that are fitted one on top of the other.

[0017] In addition, each cavity can be formed by a notch made at the same time on both plates, these two notches fitting together.

[0018] Advantageously, the foam strip has holes for receiving clamping screws connecting the crossbar to the lower tray.

[0019] Advantageously, the ends of the foam strip rest on the lateral sides of the lower tray, closing the passage at these ends.

[0020] Advantageously, at the end of the battery assembly the foam strip is tightened between the crossbar and the lower tray.

[0021] The invention also relates to an electric or hybrid motor vehicle equipped with a traction battery comprising any of the preceding characteristics, remarkable in that this battery is fixed under a floor of the vehicle's passenger compartment.

[0022] The invention will be better understood and other features and advantages will become more apparent upon reading the following description given by way of example, with reference to the accompanying drawings in which:

[0023] [Fig-1] is a longitudinal cross-sectional view along a vertical plane of a battery according to the invention;

[0024] [Fig.2] features two overlapping foam strips to close the passage under the crossbeam;

[0025] [Fig.3] shows the lower foam strip placed next to a module of cells; and

[0026] [Fig.4] shows the upper band placed above this band inferior.

[0027] Throughout the document the upper or top direction is relative to a battery fixed in a vehicle placed on a horizontal ground, the transverse direction is perpendicular to the longitudinal axis of the vehicle.

[0028] Figure 1 shows a lower battery tray 2 receiving four electrochemical cell modules 6 distributed along its length, each having a parallelepiped shape. Cross members 8 of rectangular cross-section, each inserted between two adjacent modules 6, are formed by a folded sheet comprising two horizontal wings fixed under a cover 4, and two descending faces connected at the bottom by a horizontal lower face 10.

[0029] The lower face 10 of the cross members 8, positioned a few centimeters above the lower battery tray 2, leaves between them a space 14 forming a horizontal passage connecting the areas of the two nearby cell modules 6 arranged on each side, which extends along the length of this cross member.

[0030] The [Fig.2] presents a substantially rigid foam strip 20 formed by an upper plate 24 overlapping in a fitted manner on a lower plate 22, having equivalent rectangular sections, which are formed by injection into a mold of a fire-resistant material giving them directly the finished shape.

[0031] The upper face 26 of the lower plate 22 and the lower face 28 of the upper plate 24 each have notches 30 along part of their thickness, overlapping between these plates so as to form horizontal cavities which are open towards one of the modules 6, with towards the other module a cavity bottom which is closed so as not to open onto the other side of the band 20.

[0032] The notches 30 of the lower plate 22 are formed over approximately half the height of this plate, the notches of the upper plate 24 are formed over approximately one quarter of its height.

[0033] Fig. 3 shows the lower plate 22 placed flat on the bottom of the tray 2, which is fitted between the flat lateral faces 40 of two close modules 6, and along the length which goes into contact with the two sides of the tray to close the passage at the ends of the strip 20.

[0034] Each notch 30 in the lower plate 22 receives a horizontal lateral tab 42 for securing a module 6, which is fitted into the notch to fill it, alternating between two adjacent modules along the length of the plate. Each tab 42 receives a fixing screw 44 from above, which then passes through a hole in the lower plate 22 to screw into a thread formed on the bottom of the tray 2 to secure the modules 6.

[0035] Vertical clamping screws 46 of the crossbars 8 on the bottom of the tray 2, receiving cylindrical spacers 48, also pass through holes formed in notches 30 of the strip 20 which alternate with notches receiving the tabs of modules 42. The upper ends of the screws 46 are subsequently engaged in holes in the crossbars 8 to receive from above a nut clamping the cover 4 with its crossbar on the bottom of the tray 2.

[0036] Figure 4 shows the upper plate 24 placed on the lower plate 22, with the notches 30 of these plates fitting together to cover all the mounting tabs 42 of the modules 6 snugly, without leaving any gaps around them, forming a fit within a recess. Only the ends of the clamping screws 46 of the cover 4 pass through the upper plate 24, protruding above it.

[0037] In a subsequent operation of installing the cover 4 equipped with the internal crossbars 8, their flat lower face 10 comes to rest on the top of the upper plate 24 by slightly tightening the foam when screwing the nuts onto the screws 46 in order to obtain a small compression of the two plates 22, 24 between this lower face of the crossbar and the bottom of the tray 2.

[0038] With the bottom of the cavities receiving the fixing tabs 42 closed on the two assembled plates 22, 24, and with a slight compression of these plates vertically between the cross members 8 and the bottom of the tray 2, as well as an adjustment of the ends of the plates against the sides of this bottom, a watertight partition is obtained completely closing any passage between two close areas receiving the modules 6.

[0039] In the event of a problem with cells of a module 6 involving overheating, gas release or flames, their propagation towards the The adjacent module is protected by fire-resistant materials that make up the foam in plates 22, 24, which obstructs any passage.

[0040] This allows for a delay in the heating of cells in a neighboring module 6, with the possibility of preventing the spread of a fire to the entire battery, thus improving safety.

Claims

Demands

1. Electric or hybrid vehicle traction battery forming a flat box comprising a lower tray (2) closed by a cover (4), inside the crossbeams (8) each separating two nearby areas receiving electrochemical cell modules (6), and comprising at the level of these crossbeams (8) free spaces (14) connecting two nearby areas, characterized in that it comprises a foam strip (20) fitted in each free space (14), which constitutes at the level of these crossbeams (8) fire barriers between the two nearby areas.

2. Traction battery according to claim 1, characterized in that the modules (6) have lateral fixing tabs (42) which are fitted into cavities formed on the sides of the foam strips (20).

3. Traction battery according to claim 2, characterized in that the cavities are open only in the direction of the module (6) comprising the fixing tabs (42) inserted inside, without opening out on the other side.

4. Traction battery according to any one of the preceding claims, characterized in that the foam strip (20) comprises two superimposed plates (22, 24) which are fitted one on top of the other.

5. Traction battery according to claims 3 and 4, characterized in that each cavity is formed by a notch (30) made at the same time on both plates (22, 24), these two notches (30) fitting one on the other.

6. Traction battery according to any one of the preceding claims, characterized in that the foam strip (20) has holes receiving clamping screws (46) connecting the cross member (8) to the lower tray (2).

7. Traction battery according to any one of the preceding claims, characterized in that the ends of the foam strip (20) are supported on the lateral sides of the lower tray (2) closing the passage at these ends.

8. Traction battery according to any one of the preceding claims, characterized in that at the end of the assembly of the 7 battery the foam strip (20) is tightened between the crossbar (8) and the lower tray (2).

9. Electric or hybrid motor vehicle equipped with a traction battery according to any one of the preceding claims, characterized in that this battery is fixed under a floor of the vehicle's passenger compartment.

Images