SAFETY BATTERY PACK TO PREVENT HYDROGEN PRODUCTION IN THE EVENT OF WATER-BASED LIQUID INTRUSION

Abstract

The invention relates to a battery pack (10) in particular for a motor vehicle, said battery pack (10) comprising a set (11') of power modules (11) electrically connected to each other and to output terminals (B+, B-) via electrically conductive tracks (12), each power module (11) comprising several electrochemical cells (14), - said battery pack (10) further comprising at least one controlled electrical switch (18), said controlled electrical switch (18) being shaped to open an electrically conductive track (12). Figure 3

Description

Title of the invention: SECURE BATTERY PACK TO PREVENT HYDROGEN PRODUCTION IN THE EVENT OF INTRUSION OF WATER-BASED LIQUID

[0001] The present invention relates to a secure battery pack to prevent hydrogen production in the event of intrusion of water-based liquid. The invention finds a particularly advantageous, but not exclusive, application with battery packs used in particular to provide power to an electric traction motor of a motor vehicle.

[0002] The invention can thus be implemented with battery packs installed in electric or hybrid type motor vehicles, i.e. a vehicle using an electrical energy source and another energy source, in particular a thermal, hydrogen or pneumatic energy source.

[0003] Figures 1 and 2 show a battery block 10 (called "battery pack" in English) comprising a set 11' of power modules 11, an electrical connection box 15 and a control module 20 ensuring management of the electrical energy stored by the power modules 11 as well as management of the components of the electrical connection box 15.

[0004] The power modules 11 are electrically connected to each other and to output terminals B+, B- via electrically conductive tracks 12 (called "busbars" in English). Each power module 11 is made up of several electrochemical cells 14. By "electrochemical cell" is meant a cell generating current by chemical reaction, for example of the lithium-ion (or Li-Ion) type, of the nickel-metal hydride (or Ni-Mh) type, of the nickel-cadmium (Ni-Cd) type, or even lead.

[0005] The set 11' of power modules 11 is electrically connected to high-voltage electrical equipment 13 via the electrical connection box 15 (called "junction box" in English). The electrical connection box 15 comprises at least one electrical protection fuse 16 as well as relays 17 capable of selectively authorizing or blocking an energy exchange between the battery pack 10 and the electrical equipment 13.

[0006] The high-voltage electrical equipment 13 consists in particular of one or more electric traction motors, one or more DC-DC converters making it possible to interconnect the high-voltage electrical network supplied by the battery pack 10 with a low-voltage electrical network (not shown) to which electrical consumers of the motor vehicle are connected, such as a lighting system, a human-machine interface of the touch-screen tablet type for example, acc- window or seat distributors, an engine computer, or even a starter in the case of a hybrid vehicle with a thermal engine. Any other electrical equipment requiring the use of energy from the battery pack 10 may be connected to the electrical connection box 15.

[0007] An electric traction motor draws electrical energy from the battery pack 10 to provide traction for the motor vehicle. A reversible type electric motor may also operate in generator mode, particularly during a regenerative braking phase. In this case, the electric motor may provide electrical energy to recharge the power modules 11. Energy exchanges with the battery pack 10 thus occur in both directions.

[0008] As shown in [Fig.2], when a water-based liquid 19 accumulates in the battery pack 10, it is likely to establish electrical contact between the positive B+ and negative B- terminals of the set 11' of power modules 11 at the input of the electrical connection box 15.

[0009] This liquid 19 may in particular consist of the cooling liquid of the battery pack 10 when the cooling circuit of the battery pack is faulty, or water coming from the outside entering the system due to poor sealing of the battery pack 10, or water coming from the outside via breathing pellets of the battery pack 10.

[0010] The presence of water-based liquid 19 carried by the current generated by the battery pack 10 causes the production of hydrogen and oxygen by electrolysis. This poses a safety problem since hydrogen is a highly flammable gas in the presence of oxygen.

[0011] The invention aims to effectively resolve this safety problem by proposing a battery pack, in particular for a motor vehicle, said battery pack comprising a set of power modules electrically connected to each other and to output terminals via electrically conductive tracks, each power module comprising several electrochemical cells,

[0012] - said battery pack further comprising at least one controlled electrical switch, said controlled electrical switch being shaped to open an electrically conductive track.

[0013] The invention thus makes it possible, thanks to the presence of the controlled electrical switch, to eliminate the potential difference at the terminals of the battery pack and the electrical connection box when the vehicle is asleep. Thus, even in the event of the presence of undetected liquid, the production of hydrogen and oxygen will not be possible at the terminals of the battery pack due to the opening of the electrical circuit of the battery pack. This secures the motor vehicle against the risk of explosion in the event of a leak in the seal.

[0014] According to one embodiment of the invention, said battery block comprises a tray receiving the power modules, said tray having a bottom corresponding to a lower face and an upper face opposite the bottom.

[0015] According to one embodiment of the invention, the controlled electrical switch is located at a height measured relative to the bottom of the tank greater than a liquid height which would be reached if a predetermined volume of liquid were emptied into an internal volume of the tank.

[0016] According to one embodiment of the invention, the controlled electrical switch is arranged on the upper face of the tank.

[0017] According to one embodiment of the invention, the controlled electrical switch is an electromechanical contactor.

[0018] According to one embodiment of the invention, the controlled electrical switch takes the form of a transistor or a thyristor made of a semiconductor material.

[0019] According to one embodiment of the invention, the controlled electrical switch is liquid-tight.

[0020] The invention also relates to a motor vehicle comprising a battery pack as previously defined.

[0021] According to one embodiment of the invention, said motor vehicle comprises:

[0022] - electrical equipment,

[0023] - the battery pack further comprising an electrical connection box connected electrically to the output terminals of the power module assembly,

[0024] - said electrical connection box comprising at least one protective fuse electrical system intended to protect electrical equipment as well as relays capable of selectively authorizing or blocking an energy exchange between the battery pack and the electrical equipment.

[0025] According to one embodiment of the invention, the battery pack comprises a control module configured to control, following a request to put the motor vehicle on standby, an opening of the relays of the electrical connection box as well as an opening of the controlled electrical switch.

[0026] The invention will be better understood upon reading the following description and examining the accompanying figures. These figures are given only for illustrative purposes but in no way limit the invention.

[0027] [Fig-1] [Fig. 1], already described, is a schematic representation of a battery pack according to the state of the art connected to high voltage electrical equipment;

[0028] [Fig.2] [Fig.2], already described, is a schematic perspective representation illustrating the problem of hydrogen and oxygen production following the introduction of water-based liquid inside the battery pack;

[0029] [Fig.3] [Fig.3] is a schematic representation of a battery pack according to the invention connected to high voltage electrical equipment;

[0030] [Fig.4] [Fig.4] is a schematic perspective representation illustrating the se securing the battery pack according to the invention using a controlled electrical switch preventing the production of hydrogen and oxygen following the introduction of water-based liquid inside the battery pack;

[0031] [Fig.5] [Fig.5] is a schematic perspective representation of a variant of producing a battery pack according to the invention provided with several opening means for securing it.

[0032] Identical, similar, or analogous elements retain the same reference from one figure to another.

[0033] Figures 3 and 4 show a battery block 10 (called "battery pack" in English) comprising a set 11' of power modules 11, an electrical connection box 15 and a control module 20 ensuring management of the electrical energy stored by the power modules 11 as well as management of the components of the electrical connection box 15.

[0034] The power modules 11 are electrically connected to each other and to output terminals B+, B- via electrically conductive tracks 12. In this case, the power modules 11 are electrically connected in series with each other. Thus, the positive terminal of a power module 11 is connected, via a conductive track 12, to a negative terminal of an adjacent power module 11, which has its positive terminal connected, via a conductive track 12, to a negative terminal of another adjacent power module 11 and so on. Alternatively, one or more groups of power modules 11 may be electrically connected in parallel with one or more other groups of power modules 11.

[0035] The conductive tracks 12 are made of an electrically conductive material, for example copper. The conductive tracks 12 may have a round or rectangular section. If necessary, an insulating material may be overmolded onto the conductive tracks 12.

[0036] Each power module 11 comprises several electrochemical cells 14. By "electrochemical cell" is meant a cell generating current by chemical reaction, for example of the lithium-ion (or Li-Ion) type, of the nickel-metal hydride (or Ni-Mh) type, of the nickel-cadmium (Ni-Cd) type, or even lead. The power modules 11 are preferably identical modules. However, as a variant, the power modules 11 could be of different chemistry.

[0037] The battery pack 10 preferably delivers a voltage equal to or greater than 48 Volts. More generally, the voltage of the battery pack 10 could be between 12V and 1000V.

[0038] The assembly 11' of the power modules 11 is electrically connected to high-voltage electrical equipment 13 via an electrical connection box 15 (called a "junction box" in English). For this purpose, the assembly 11' comprises output terminals, namely a positive output terminal B+ and a negative output terminal B-, to which the electrical connection box 15 is electrically connected. The electrical connection box 15 comprises at least one electrical protection fuse 16 intended to protect the high-voltage electrical equipment as well as relays 17 capable of selectively authorizing or blocking an energy exchange between the battery pack 10 and the high-voltage electrical equipment 13.

[0039] The high-voltage electrical equipment 13 consists in particular of one or more electric traction motors, one or more DC-DC converters making it possible to interconnect the high-voltage electrical network supplied by the battery pack 10 with a low-voltage electrical network to which electrical consumers of the motor vehicle are connected, such as a lighting system, a human-machine interface of the touch-screen tablet type for example, window or seat actuators, an engine computer, or even a starter in the case of a hybrid vehicle. Any other equipment requiring the use of the energy from the battery pack 10 may be connected to the electrical connection box 15.

[0040] An electric motor draws electrical energy from the battery pack 10 to provide traction for the motor vehicle. A reversible type electric motor may also operate in generator mode, in particular during a regenerative braking phase. In this case, the electric motor may provide electrical energy to recharge the battery pack 10. Energy exchanges with the battery pack 10 thus occur in both directions.

[0041] The battery pack 10 further comprises at least one controlled electrical switch 18. The controlled electrical switch 18 is shaped to open an electrically conductive track 12.

[0042] In this case, a controlled electrical switch 18 is electrically connected in series between two power modules 11. The controlled electrical switch 18 can thus be arranged between a portion of a conductive track 12 connected to a positive terminal of a power module 11 and another portion of the conductive track 12 connected to a negative terminal of an adjacent power module 11.

[0043] The controlled electrical switch 18 may take a closed state allowing the passage of current from one power module 11 to another and an open state in which the controlled electrical switch 18 prevents the passage of current in order to avoid the creation of hydrogen in the event of a rise in liquid 19 establishing a short circuit between the output terminals B+, B- of the battery pack 10.

[0044] Alternatively, the controlled electrical switch 18 is arranged on an electrical track electrically conductive connected to an output terminal B+ or B-.

[0045] The controlled electrical switch 18 is preferably an electromechanical contactor. This makes it possible to provide galvanic isolation in the opening situation. Alternatively, the controlled electrical switch 18 takes the form of a transistor or a thyristor made of a semiconductor material. Preferably, the controlled electrical switch 18 is liquid-tight.

[0046] Alternatively, the controlled electrical switch 18 may be arranged on a conductive track 12 extending between an output terminal B+, B- of the battery pack 10 and a power module 11 electrically connected to this output terminal. The controlled electrical switch 18 may thus be arranged on the conductive track 12 extending between the positive terminal B+ of the battery pack 10 and a power module 11 connected directly to this positive terminal B+ via this conductive track. The controlled electrical switch 18 may also be arranged on the conductive track 12 extending between the negative terminal B- of the battery pack 10 and a power module 11 connected directly to this negative terminal B- via this conductive track.

[0047] In the example shown, the battery pack 10 comprises a tray 21 receiving the power modules 11, as shown in [Fig. 4]. The tray 21 may for example have a parallelepiped shape. The tray 21 has a bottom 21.1 corresponding to a lower face and an upper face 21.2 opposite the bottom 21.1. If necessary, the upper face may be covered by a lid (not shown).

[0048] The controlled electrical switch 18 is located at a location protected from a possible rise of liquid 19 inside the tank 21 of the battery pack 10. Thus, the controlled electrical switch 18 is located at a height L1 measured relative to a bottom of the tank 21 greater than a height L0 of liquid (also measured relative to the bottom of the tank 21) which would be reached if a predetermined volume of liquid corresponding in particular to the entirety of the liquid contained in a cooling circuit of the battery pack 10 were emptied inside an internal volume of the tank 21. Such a predetermined volume of liquid depends on the characteristics of the cooling circuit used. This predetermined volume of liquid is generally between 5 liters and 10 liters.

[0049] Preferably, the controlled electrical switch 18 is arranged on the upper face 21.2 of the tray 21. Alternatively, the controlled electrical switch 18 is arranged on a lateral face of the tray 21 at a height L1 greater than the height L0.

[0050] Furthermore, the control module 20 is capable of ensuring in particular control of the piloted electrical switch 18 and the relays 17 of the electrical connection box 15.

[0051] Thus, when the motor vehicle is in operation, that is to say in a phase of recharging the battery pack 10 or in a driving phase, the control module 20 controls the relays 17 so as to authorize the transfer of energy. electrical connection between the battery pack 10 and the electrical equipment 13 via the electrical connection box 15. The controlled electrical switch 18 is then in the closed state.

[0052] When the motor vehicle is asked to go into standby mode, that is to say to interrupt the energy exchanges with the battery pack 10, the control module 20 commands an opening of the relays 17 of the electrical connection box 15 as well as an opening of the controlled electrical switch 18.

[0053] In this situation, the liquid level 19 can reach a height bringing the inputs of the electrical connection box 15 into electrical contact without the risk of creating hydrogen and oxygen at its terminals due to the opening of the controlled electrical switch 18 making it possible to no longer have any voltage at the input of the electrical connection box 15.

[0054] In the embodiment of [Fig.5], two opening means 18 are provided electrically connected in series in the circuit of the power modules 11. Of course, it is possible to integrate more than two opening means 18.

Claims

Claims

1. Motor vehicle comprising: - electrical equipment (13), - a battery pack (10), said battery pack (10) comprising: - a set (11') of power modules (11) electrically connected to each other and to output terminals (B+, B-) via electrically conductive tracks (12), each power module (11) comprising several electrochemical cells (14), - an electrical connection box (15) electrically connected to the output terminals (B+, B-), and comprising at least one electrical protection fuse (16) intended to protect the electrical equipment (13) as well as relays (17) capable of selectively authorizing or blocking an energy exchange between the battery pack (10) and the electrical equipment (13), characterized in that said battery pack (10) further comprises: - at least one controlled electrical switch (18),said controlled electrical switch (18) being shaped to open an electrically conductive track (12), - a control module (20) configured to control, following a request to put the motor vehicle on standby, an opening of the relays (17) of the electrical connection box (15) as well as an opening of the controlled electrical switch (18).,

2. Vehicle according to claim 1, characterized in that the battery pack comprises a tray (21) receiving the power modules (11), said tray (21) having a bottom (21.1) corresponding to a lower face and an upper face (21.2) opposite the bottom (21.1).

3. Vehicle according to claim 2, the battery pack (10) comprising a cooling circuit, characterized in that the controlled electrical switch (18) is located at a height (L1) measured relative to the bottom of the tank (21) greater than a height (L0) of liquid which would be reached if a predetermined volume of liquid, corresponding to the entirety of a liquid contained in this cooling circuit of the battery pack 10, were emptied inside an internal volume of the tank (10).

4. Vehicle according to claim 2 or 3, characterized in that the controlled electrical switch (18) is arranged on the upper face (21.2) of the tray (21).

5. Vehicle according to any one of claims 1 to 4, characterized in that the controlled electrical switch (18) is an electromechanical contactor.

6. Vehicle according to any one of claims 1 to 4, characterized in that the controlled electrical switch (18) takes the form of a transistor or a thyristor made of a semiconductor material.

7. Vehicle according to any one of claims 1 to 6, characterized in that the controlled electrical switch (18) is liquid-tight.

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