Motor vehicle battery pack and gas discharge device

Abstract

Title of the invention: Gas discharge device for a motor vehicle battery pack The invention relates to a motor vehicle battery pack (2) comprising a casing (4), which is configured to house electrical energy storage modules, and at least one cover (8) able to cover said casing (4), the at least one cover (8) comprising an inner face (10) positioned facing the casing (4), the battery pack (2) comprising at least one seal (14) arranged between the inner face (10) of the cover (8) and the casing (4), the at least one seal (14) and / or the casing (4) and / or the cover (8) being configured to form at least one weakened area (18) of the seal that is dimensioned to allow discharge of gases under a predetermined pressure or temperature of these gases.

Description

[0001] DESCRIPTION

[0002] TITLE: MOTOR VEHICLE BATTERY PACK AND GAS EVACUATION DEVICE

[0003] The present invention relates to the field of motor vehicle batteries and more particularly concerns that of safety devices allowing the evacuation of gases which may appear in the batteries in the event of thermal runaway of the electrochemical cells making up these batteries.

[0004] Following a short circuit or an impact, a defective electrochemical cell present in the battery pack may overheat and the rise in temperature of this cell may generate the release of hot fumes and thermal runaway which spreads from cell to cell. In order to limit the degradation of each of the cells and the risk of explosion which could result from this thermal runaway, an evacuation of the gases present in the battery pack at the time of the thermal runaway is sought, the gases having to be evacuated in areas which do not present a danger to the health of the passengers having to evacuate the vehicle at that moment or of the emergency services coming to the aid of the passengers.

[0005] Currently, the devices used in motor vehicles for the evacuation of gases produced by thermal runaway of battery cells consist of a valve arranged on a wall of the housing or the cover of the battery pack, this valve being configured to trigger at a certain pressure of the gases trapped within the battery pack.

[0006] These evacuation devices known from the state of the art, however, have several drawbacks. A first drawback is that the valves tend to open too late so that the temperature of the gases is high enough to damage the entire battery pack. Furthermore, the valves are large parts, which has the effect of increasing the size of the battery pack, while the size of the vehicle must be controlled. Furthermore, the valves expel the smoke gases from the battery pack randomly, thus risking projecting them into an area where passengers in the vehicle may be present.

[0007] There is currently a need to improve the configuration of the gas evacuation device of a motor vehicle battery pack in order to reduce the dimensions of the battery pack and thus facilitate its integration into the vehicle while ensuring the safety of its passengers.

[0008] The present invention falls within this context and proposes a gas evacuation device comprising one or more seals respectively comprising a weakening zone configured to form the seal, with the rest of the seal, of the battery pack in a normal operating mode and to yield and allow the evacuation of the smoke gases produced in the event of thermal runaway.

[0009] More particularly, the main subject of the present invention is a motor vehicle battery pack comprising a housing configured to house electrical energy storage modules and at least one cover capable of covering said housing, the at least one cover comprising an internal face arranged opposite the housing, the battery pack comprising at least one seal arranged between the internal face and the housing, the at least one seal and / or the housing and / or the cover being configured to form a gas evacuation device with at least one weakening zone of the seal sized to allow evacuation of gas under a determined pressure or temperature of these gases.

[0010] A battery pack is used in particular in electric or hybrid motor vehicles to provide the energy needed to propel the vehicle. The battery pack comprises a rigid casing in which a plurality of electrochemical cells are housed, which must be protected from impacts. The casing acts as a mechanical protection for the electrochemical cells, ensuring the storage and supply of electrical energy to the vehicle.

[0011] These electrochemical cells are arranged next to each other against a bottom wall of the housing. In one embodiment, the bottom wall is opposite a first end of said housing intended to be covered by the at least one cover. According to different alternatives, the bottom wall can be formed in one piece with the housing or be formed by a second cover.

[0012] Generally, the cover may form either wall of the battery pack, and for example be positioned laterally between an upper wall and a lower wall, when referring to the arrangement of the battery pack in the vehicle relative to a vertical direction.

[0013] The housing is sealed with a lid to prevent dirt or moisture from entering the housing and disrupting the operation of the electrochemical cells housed within it. It is therefore customary to have gaskets between the housing and the lid closing the battery pack to ensure the latter's watertightness.

[0014] The electrochemical cells of the battery pack increase in temperature during their operation. Temperature regulation means, in particular comprising means of recirculation and / or projection of a dielectric cooling fluid, or indirect cooling means by glycol water or even cooling means by recirculation and / or projection of a glycol water fluid are present in the battery pack to regulate the temperature of the cells in a standard operating mode. When the cells experience a malfunction, and more particularly, when the vehicle suffers a violent shock and the integrity of the cells is impacted, unusual overheating of the cells may appear and spread gradually in a thermal runaway involving the presence within the battery pack of particularly hot and high-pressure gases, which require their evacuation in order to avoid the risk of an explosion.

[0015] The housing according to the invention, as presented, allows the evacuation of these gases present in quantity during a thermal runaway, so that it only needs to be implemented when a malfunction or shock has occurred. This evacuation is done here via the weakened zone which is, according to the invention, a zone of the seal forming an evacuation device. It is through this weakened zone that the gases can pass in order to be expelled from the battery pack when the evacuation device must play its role, that is to say as mentioned when a malfunction or shock has occurred.According to the invention, there is therefore a seal which plays its sealing role in normal operation, in particular when the pressure or temperature of the gas within the battery pack is normal, i.e. lower than a determined threshold value, and of which a part, namely the weakened zone, is capable of taking on a second configuration under the effect of a pressure or a temperature going beyond this threshold value, to allow the evacuation of gas.

[0016] This weakened zone is formed by means of a part of the battery pack which in normal operation has another function, namely the seal, so that a functional integration is achieved which makes it possible to do without additional equipment or part to carry out the evacuation function, which then represents an economic gain.

[0017] According to an optional characteristic of the invention, the weakening zone is formed by a local deformation of the at least one sealing gasket.

[0018] Local deformation means a change in the shape and / or dimensions of the seal over a small portion of it, such that the shape and / or dimensions of the weakened area are different from those of the rest of the seal.

[0019] According to an optional characteristic of the invention, the at least one sealing gasket is formed from a material injected around the perimeter of the battery pack, on one face of the housing and / or the cover.

[0020] According to an optional feature of the invention, said material is a polyurethane foam and / or a silicone foam. According to an optional feature of the invention, the at least one sealing gasket is an elastomer gasket, deposited in one piece between the housing and the cover.

[0021] According to an optional feature of the invention, said seal is deposited in a groove formed in the thickness of the housing and / or the cover. The groove is a peripheral groove of the housing and / or the cover, that is to say which extends continuously all around the housing in which the cells of the battery pack are housed. The groove has a cross-sectional shape which is substantially similar to the shape of the portion of the seal which is housed in the groove. A groove may be formed in the housing and another groove may be formed in the cover to each receive a portion of the seal.

[0022] According to an optional characteristic of the invention, the weakening zone of the at least one seal extends over a distance of the order of 1 to 50% of the peripheral dimension of the seal, preferably 1 to 30%, in particular 5% to 25%.

[0023] These values ​​are a good compromise between, on the one hand, the need to have a sufficient extension distance from the weakening zone to evacuate a significant quantity of gas in the event of a malfunction or shock likely to generate thermal runaway and, on the other hand, the need to have a seal that reliably ensures its sealing function in standard operation.

[0024] According to an optional characteristic of the invention, the groove for receiving the at least one sealing joint has a larger section at the weakening zone than that of the rest of the groove.

[0025] At the weakened zone, the groove has a larger cross-section than the cross-section of the rest of the groove into which the rest of the seal is inserted. This larger dimension can be a width, in the plane of the housing or cover from which the seal emerges, or a depth in the material of the housing or cover. Thus, the seal at the weakened zone can be displaced within the groove when the pressure of the gases, and in particular of the hot gases present within the battery pack in the event of a malfunction or impact, is greater than a threshold value, which allows the gases to pass more easily.

[0026] According to another characteristic, the at least one cover and / or the housing comprises a support zone which is in contact with the at least one seal interposed between this cover and the housing, the support zone comprising a relief, in particular a groove, capable of cooperating with the at least one seal in its weakened zone.

[0027] The support zone is opposite the seal and the relief is more particularly opposite the weakening zone of the seal.

[0028] The relief can be made in one piece in the housing or be added to the internal face of the cover. The relief can for example be a boss. By closing the housing using the cover, the relief arranged in the latter can thus push deeper a local area of ​​the seal arranged opposite the relief and corresponding to the weakened area. This results in a compression rate of the seal in the weakened area which is different, more particularly higher, at this precise point of the seal compared to the rest of the seal.

[0029] It is understood that a relief in the form of a boss makes it possible to locally generate a compression rate higher than the standard compression rate applied to the rest of the joint, which has the effect of locally weakening the joint and creating a weakening zone more likely to subsequently deform under high gas pressure or temperature during thermal runaway.

[0030] Alternatively, the relief can be a cavity forming a clearance of material in the thickness of the cover, so that more space is left locally for the seal when the cover is attached to the housing. This also induces a different compression ratio, but in this alternative it is lower at this precise point of the seal, which again allows the creation of a weakening zone.

[0031] It is understood that a relief in the form of a cavity makes it possible to locally generate a compression rate lower than the standard compression rate applied to the rest of the seal, which has the effect of creating a weakening zone in which the sealing gasket is still able to compress under the effect of pressure or temperature of the gases during thermal runaway and consequently to allow these gases to pass between the housing and / or the cover on the one hand and the compressed seal in the weakening zone.

[0032] According to an optional characteristic of the invention, the weakened zone of the at least one seal has a compression rate lower than the compression rate of the rest of the seal.

[0033] This difference in compression rate of the weakening zone can be obtained in particular by a cavity formed in the cover as mentioned, by a peripheral groove dimension in the housing which locally has, in the weakening zone, larger dimensions than those of the rest of the groove, or even by a heterogeneous structural composition of the material, for example a two-material design of the sealing gasket, which allows a difference in local compression rate under the same pressure force of the cover on the housing.

[0034] According to an optional characteristic of the invention, at least two sealing gaskets are interposed between the housing and the at least one cover, around the periphery of the housing, each gasket being radially offset from the adjacent gasket in a first radial direction, each gasket comprising a weakening zone, the weakening zone arranged in a first gasket being in particular angularly offset relative to the weakening zone arranged in a second gasket.

[0035] The concept of radial and angular offset must be understood broadly, independently of the overall shape of the seals in the contact plane between the housing and the cover. In particular, the concepts of radial and angular offset do not necessarily imply an overall circular shape of the seal, but can be understood with a substantially rectangular overall shape. The concept of radial offset is understood by considering the radial direction going from the inside of the battery pack to the outside of it, through the walls of the housing. It must thus be understood that a radial offset implies the presence of a first seal arranged on the periphery of the housing as close as possible to the electrochemical cells housed in the battery pack and the presence of a second seal arranged on the same periphery more distally from the latter, in other words towards the outside of the housing.

[0036] The concept of angular offset is understood by considering the peripheral path around the cells of the battery pack, on the end faces of the walls of the case intended to be in contact with the cover.

[0037] Thus, the angular offset implies that the first weakening zone arranged in the first joint is offset so that it is not arranged opposite the second weakening zone arranged in the second joint.

[0038] This configuration allows for the regulation and optimization of gas evacuation. An abnormal pressure or temperature of the gases during thermal runaway will cause the first weakening zone arranged in the first seal located closest to the electrochemical cells to break, the first weakening zone being able to be located on the periphery of the first seal closest to the point that is likely to be the hottest within the battery pack. The gases will then circulate between the two seals until they encounter the second weakening zone arranged in the second seal.This second weakening zone is located on the periphery of the second seal as close as possible to the area which has been identified as a safe zone for the evacuation of high pressure and high temperature gases, i.e. an area where vehicle occupants or emergency services are not expected to be in the event of thermal runaway and evacuation or intervention on the vehicle.

[0039] According to an optional characteristic of the invention, a motor vehicle battery pack comprises at least one housing, a cover configured to cover a first end edge of the housing and an additional cover to cover a second end edge of the housing opposite the first end edge, said battery pack comprising a gas evacuation device as previously mentioned arranged between the housing and the cover and a gas evacuation device as previously mentioned arranged between the housing and the additional cover.

[0040] The gas evacuation device as previously mentioned is arranged between the housing and the cover and / or the additional cover. The presence of an evacuation device arranged between the housing and each cover thus makes it possible to improve the gas evacuation performance of the battery pack. In what follows, the passages mentioning the cover and the additional cover can apply with interchanged positions of these two elements.

[0041] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and examples of embodiment given for informational and non-limiting purposes with reference to the appended drawings on the other hand, in which:

[0042] [Fig. i] schematically illustrates a motor vehicle battery pack equipped with an evacuation device having a weakening zone according to one embodiment of the invention;

[0043] [Fig. 2] schematically illustrates a battery pack equipped with the evacuation device of the invention, according to a first alternative;

[0044] [Fig. 3] schematically illustrates a battery pack equipped with the evacuation device of the invention, according to a second alternative;

[0045] [Fig. 4] schematically illustrates, in section, a portion of a battery pack in which the evacuation device is in a standard configuration;

[0046] [Fig. 5] schematically illustrates, in section, a different portion of the battery pack illustrated in Figure 4, this figure illustrating more particularly the weakening zone of the evacuation device;

[0047] [Fig. 6] schematically illustrates a motor vehicle battery pack equipped with a discharge device according to a second embodiment. The characteristics, variants and the different embodiments of the invention may be associated with each other, in various combinations, to the extent that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of characteristics described below in isolation from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage and / or to differentiate the invention from the state of the prior art.

[0048] As a reminder, the invention relates to a battery pack in which a weakening zone is arranged in a seal to allow the evacuation of gases resulting from thermal runaway of the electrochemical cells of this battery pack, this weakening zone also having to ensure the sealing of the battery pack in the event of normal operation.

[0049] Figure 1 illustrates a battery pack 2. The battery pack 2 comprises a housing 4 formed by a plurality of walls and which has the function of protecting electrochemical cells 3 of the battery pack, these electrochemical cells allowing the storage and supply of electrical energy. These electrochemical cells 3 are arranged against a bottom wall 12 of the housing. The housing here has the shape of a rectangular parallelepiped, with two-by-two parallel walls 6a, 6b and 6c, 6d and which form a frame 16. The frame 16 has a first end edge 17 of the housing 4, which is arranged opposite the bottom wall 12 and which delimits an opening of the housing through which the electrochemical cells 3, some of which are shown in Figure 1 without their number being representative here, are inserted into the housing formed by the housing.The first end edge 17 is capable of being covered by a cover 8 shown in dotted lines in Figures 1 and 2 to make visible the interior of the housing and the arrangement of the evacuation device associated with the battery pack according to the invention. More precisely, the cover 8 closes the housing by bearing on the first end edge 17, over the entire periphery of the frame 16, in a stacking direction E. The cover 8 comprises an internal face 10 arranged opposite the frame 16 and here the bottom wall 12. The first end edge 17 of the frame 16 is a flat and peripheral surface of the housing 4 intended to be opposite the internal face 10 of the cover 8.

[0050] Alternatively, the first end edge 17 is opposite a second end edge of the frame 16 on which an additional cover can be affixed to form the bottom wall 12. In the following, what will be described as a means of sealing and evacuating gas in the event of thermal runaway for the cover 8 and the first end edge 17 can be applied in the same way to the additional cover and to the second end edge.

[0051] It is understood here that the cover can be affixed to the upper part of the housing, precisely against the first end edge 17 or else be affixed to the lower part of the latter, precisely against the second end edge of the frame 16 which in this second configuration, is called additional cover. Alternatively, the cover 8 can form a side wall of the housing 4. Between the frame 16 and the internal face 10 of the cover 8 is arranged a seal 14. The seal 14 is configured mainly to ensure, in a standard operating mode, the sealing of the battery pack 2 and thus protect the electrochemical cells from dirt and moisture likely to penetrate inside the latter.The sealing of the battery pack also makes it possible to preserve the effectiveness of the cooling means of the electrochemical cells within the battery pack 2, in particular by avoiding the leakage of dielectric cooling fluid or glycol water. It is understood here that the sealing gasket 14 is arranged between the internal face 10 of the cover 8 and the frame 16 once the electrochemical cells are housed within the housing 4 and the cover 8 is affixed to the frame 16 forming this housing 4.

[0052] The seal 14 may be deposited on a flat face of the first end edge 17 of the frame, in particular by a robot configured to inject a fluid material onto a seal receiving area. For example, the seal may be polyurethane foam or silicone injected directly onto the frame 16 before the cover is folded down onto this frame.

[0053] Alternatively, the seal 14 can be deposited in a groove 21 arranged in the internal face 10 of the cover 8 or in the frame 16, in particular when the sealing gasket 14 is formed by an elastomer seal of predefined shape, which fills the groove around the entire periphery of the frame 16.

[0054] According to the invention, the seal 14 comprises a weakening zone 18. This weakening zone 18 is a local portion of the seal 14 which has a difference compared to the rest of the seal, this difference giving the weakening zone the possibility of ensuring the sealing function of the seal in a standard operating mode and of taking a different configuration from the rest of the seal in a degraded operating mode, in particular when the battery pack experiences thermal runaway, for example following an impact suffered by the vehicle.

[0055] This difference in the weakening zone compared to the rest of the seal may in particular be a different structural configuration, due to the presence of a different material in a seal made of two materials, or due to a different compression ratio in the weakening zone for example. The difference in the weakening zone may also consist of dimensions different from those of the rest of the seal 14.

[0056] This weakening zone 18 is in particular configured to take a second configuration, allowing the evacuation of gas from the battery pack, under the effect of an abnormal pressure and / or temperature of the gases produced by the thermal runaway of the electrochemical cells 3 during a malfunction of the battery pack, for example after an impact suffered by the vehicle.

[0057] As mentioned, the weakening zone 18 remains in its original configuration when the pressure and temperature of the gases within the battery pack are within normal value ranges, which allows the seal as a whole to retain its sealing function. Conversely, when the pressure of the gases present inside the battery pack is above the pressure threshold considered normal, and / or the temperature of the gases present inside the battery pack is above the temperature threshold considered normal, the weakening zone 18 takes on another configuration, and in particular moves or changes shape and / or dimensions, which allows the passage of the gases present in the battery pack to the outside of the battery pack. It is understood here that the weakening zone 18 has a dual function, both that of sealing and that of evacuating the gases.The pressure or temperature threshold beyond which the weakening zone takes on a second configuration allowing the evacuation of gases from the battery pack can be in the order of 200 mbar to 400 mbar. These thresholds are defined in particular to ensure the safety of vehicle occupants and emergency services and to prevent an explosion within the battery pack.

[0058] As mentioned, an additional seal, similar to the seal 14, could be arranged on the additional cover intended to cover the second end edge of the frame 16 in order to provide a sealing role at this second end edge.

[0059] The weakened zone 18 is located around the perimeter of the seal at a specific location to allow the gases to escape safely, in other words at a location where the gases are directed away from the passengers of the vehicle in which the battery pack 2 is integrated.

[0060] According to an alternative not shown here, the seal 14 may comprise several weakening zones 18, provided that each weakening zone is located on the periphery at a specific place allowing the gases to be safely evacuated.

[0061] In order to increase the quantity of gases evacuated in the event of thermal runaway, the extension distance of the weakening zone 18 relative to the peripheral dimension of the seal 14 may be extended, but it is advisable not to weaken the seal over too great a distance so that it can retain its integrity and its sealing function in a standard operating mode of the vehicle and the battery pack. For example, a weakening zone 18 may extend over a distance of the order of 1 to 50% of the peripheral dimension of the seal 14, preferably 1 to 30%, in particular 5% to 25%.

[0062] Figure 2 illustrates one of the exemplary embodiments of the weakening zone 18, which is here formed by the cooperation of the seal 14 with a groove for receiving the seal, the groove having at least one dimension which is increased locally, at the level of the weakening zone.

[0063] In other words, the area of ​​the seal intended to be the weakening area 18 is arranged in a portion of a groove 21 which has a section of a larger dimension than the section dimension of the rest of the groove in which the rest of the seal 14 is arranged. In the example illustrated, the portion of the groove 21 which is at the level of the weakening area has a radial dimension, that is to say in a direction which goes from the inside of the battery pack to the outside of the battery pack by crossing a wall of the frame 16, which is larger than the corresponding dimension of the seal. It will be understood that without departing from the context of this exemplary embodiment, it is the depth, that is to say the dimension in the stacking direction E previously mentioned, of this portion of the groove which could be enlarged.

[0064] At the location where the dimension of the groove is larger, that is to say at the level of the weakening zone, the seal 14 has more room to expand when it is compressed by closing the cover and the compression ratio of the seal is locally lower than that of the rest of the seal. The weakening zone 18 of the seal can in this way substantially move in its groove portion under an abnormal pressure and / or temperature of the gases so as to allow the latter to pass more easily when thermal runaway of the electrochemical cells 3 occurs.

[0065] It is understood that in a standard configuration, that is to say with a gas pressure which does not affect the original shape of the compressed seal, the seal as a whole and in particular the weakened zone, extends so as to completely fill the groove and ensures its sealing function.

[0066] Figure 3 illustrates another example of embodiment of the weakening zone 18. In this example, the weakening zone 18 is produced by local deformation of the seal 14.

[0067] This local deformation is obtained by the presence on the cover, in particular on the internal face of the cover, of a boss forming a relief 20. More particularly, this relief 20 is arranged in the support zone of the cover, that is to say in the peripheral zone on the internal face of the cover, which is intended to come against the first end edge 17 and against the sealing gasket. This type of relief 20 here has the role of pushing the portion of the seal 14 opposite the relief 20 deeper when the cover 8 is brought against the housing and in particular against the first end edge 17 of the frame 16 to create a weakening zone 18 shown in hatched form in FIG. 3. It is understood here that the presence of the relief 20 exerts on the corresponding portion of the seal, that is to say the weakening zone 18, a compression rate which is greater than the standard compression rate applied to the rest of the seal 14.This high compression ratio contributes to weakening the seal to such an extent that the occurrence of a gas pressure or temperature above a threshold value, particularly in the case of thermal runaway, is likely to cause the seal to fail at the weakened zone.

[0068] The relief boss 20 may be rectangular, round, or of any other shape, provided that in this alternative, it projects sufficiently to locally provide a compression rate on the seal 14 which goes beyond the normal compression rate applied to the rest of the seal.

[0069] Figures 4 and 5 illustrate local portions of a battery pack comprising an evacuation device according to an exemplary embodiment of the invention, with respectively a sectional view of the seal 14 between the cover 8 and the frame 16 of the housing in an area remote from the weakening zone (figure 4) and a sectional view of the seal 14 between the cover 8 and the frame 16 of the housing at the weakening zone 18. These figures make it possible to illustrate an exemplary embodiment of the weakening zone, by difference in the compression rate applied to the seal from one area of ​​this seal to another.

[0070] Figure 4 illustrates a local portion in which the compression ratio of the seal is a standard compression ratio, applied when the cover 8 is folded down onto the housing. This compression ratio applies to the entire seal 14 except in the weakened zone 18. The cover 8 is brought against the frame 16 at a distance Di from the first end edge 17 so as to compress the seal 14 according to a standard compression ratio of between 40% and 60%.

[0071] Figure 5 illustrates the weakening zone, in which the compression ratio of the seal is lower than the standard compression ratio, in particular due to the presence of a cavity locally leaving more room for the seal to expand when the cover is brought against the housing.

[0072] More particularly, the cavity forms a relief 19 formed in the thickness of the cover 8. Here again, the relief 19 is arranged in the bearing zone of the cover, that is to say in the peripheral zone on the internal face of the cover, which is intended to come against the first end edge 17 and against the seal. As can be seen in this figure 5, at this weakening zone, the cover 8 is as a whole at the same distance Di from the frame 16, but the cavity forming the relief 19 ensures a clearance distance D2 which is greater than this distance Di, so that the seal has more room to expand. This type of relief thus generates a compression rate of the seal 14 which is lower than the standard compression rate, and which can in particular be between 20% and 30%, thus forming the weakening zone 18.It is understood that this weakening zone 18, being less compressed than its properties allow, is still capable of compressing under the effect of pressure or temperature of the gases during thermal runaway, which has the consequence of allowing these gases to pass between the housing 4 and / or the cover 8.

[0073] Figure 6 shows a second embodiment of the invention. This second embodiment differs from the first embodiment in that the gas evacuation device comprises two seals 14, 24 arranged between the inner face 10 of the cover 8 and the same end edge of the frame 16 of the housing 4. A first seal 14 forms an inner seal, which is arranged on the first end edge 17 of the frame 16 of the housing 4 as close as possible to the electrochemical cells 3 and a second seal 24 forms an outer seal, which is also arranged on the first end edge 17 and which is radially offset relative to the inner seal towards the outside of the frame. The first seal 14 comprises a first weakening zone 18a. The second seal 24 comprises a second weakening zone 18b.Each of these weakening zones can be produced according to one of the previously mentioned embodiments of the invention, without this being limiting of the invention since each seal has a weakening zone capable of taking a configuration participating in the sealing function, that is to say impermeable to the passage of gas in particular, during standard operation, and taking a second configuration allowing the passage of gas at high pressure and / or high temperature in the case of thermal runaway within the battery pack.

[0074] Figure 7 shows a third embodiment of the invention. This third embodiment differs from the second embodiment in that the gas evacuation device comprises two seals 14, 24 arranged between the internal face 10 of the cover 8 and the same end edge of the frame 16 of the housing 4, but the first seal (14) peripherally surrounds the entire periphery of the battery pack (2), the face of the housing (4) and / or the cover (8), while the second seal (24) is present on a partial portion of the periphery of the battery pack (2), the face of the housing (4) and / or the cover (8).

[0075] Thus, doubling the seal only near the weakened zone ensures the sealing of the zone in a normal situation, despite the presence of a weakened zone (18).

[0076] In an alternative not shown here, the inner seal and / or the outer seal could respectively comprise several weakening zones 18.

[0077] The first weakening zone 18a arranged on the first seal 14 and the second weakening zone 18b arranged on the second seal 24 are angularly offset so as not to face each other. In other words, the weakening zones of each of the seals are not radially facing each other and the gases discharged from the inside of the battery pack to the outside must follow a serpentine path to exit the battery pack.

[0078] The first weakening zone 18a arranged in the first seal 14 may be a zone located in a specific place, and in particular as close as possible to a place where an increase in temperature and / or pressure of the gases present in the battery pack can be identified early. The second weakening zone 18b arranged in the second seal 24 may be a zone located in a place identified as having no impact on the safety of the vehicle passengers during the evacuation of the gases. Thus, the high pressure and / or temperature gases cause the first weakening zone 18a to yield or deform in order to pass through the first seal and then they circulate between the cover 8 and the frame 16 between the two seals until they reach the second weakening zone 18b to cause it to yield in turn, then allowing the gases to be evacuated from the battery pack 2 without endangering the vehicle passengers.

[0079] In this context, it is possible to provide two different pressure or temperature thresholds, respectively associated with one of the two seals. As a non-limiting example of the invention, these threshold values, beyond which the weakening zone takes on a second configuration allowing the evacuation of gases from the battery pack, can be of the order of 200 mbar to 300 mbar for the first weakening zone 18a of the first seal 14 and of the order of 400 mbar and beyond for the second weakening zone 18b of the second seal 24.

[0080] As just described, the invention achieves the aims it has set itself, by proposing a device for evacuating high-pressure and / or high-temperature gases, which is intended to avoid a risk of explosion in a battery pack in the event of thermal runaway and which does not require the addition of expensive and bulky valves to a battery pack. The evacuation device according to the invention locally modifies the properties of the seal originally provided on the battery pack for conventional sealing functions, so as to integrate a function for evacuating high-pressure and / or high-temperature gases into a part already provided.This saves space and reduces the costs of achieving this function, by forming a weakened zone in the seal that can break or be modified under extreme conditions, particularly in the event of a violent impact to the vehicle and a risk of explosion, allowing gases to pass outside the vehicle.

Claims

CLAIMS 1. Motor vehicle battery pack (2) comprising a housing (4) configured to house electrical energy storage modules and at least one cover (8) capable of covering said housing (4), the at least one cover (8) comprising an internal face (10) arranged opposite the housing (4), the battery pack (2) comprising at least one seal (14) arranged between the internal face (10) of the cover (8) and the housing (4), the at least one seal (14) and / or the housing (4) and / or the cover (8) being configured to form at least one weakening zone (18) of the seal sized to allow evacuation of gases under a determined pressure or temperature of these gases.

2. Battery pack (2) according to claim 1, characterized in that the at least one seal (14) has a local deformation, in particular a shape and / or dimensions different from those of the rest of the seal, so as to form the weakening zone (18).

3. Battery pack (2) according to any one of claims 1 or 2, characterized in that the at least one sealing gasket (14) is formed from a material injected around the perimeter of the battery pack (2), on one face of the housing (4) and / or the cover (8).

4. Battery pack (2) according to the preceding claim, characterized in that said material is a polyurethane foam and / or a silicone foam.

5. Battery pack (2) according to any one of claims 1 or 2, characterized in that the at least one sealing gasket (14) is an elastomer gasket, deposited in one piece between the housing (4) and the cover (8).

6. Battery pack (2) according to any one of the preceding claims, characterized in that the weakening zone (18) of the at least one seal (14) extends over a distance of the order of 1 to 50% of the peripheral dimension of the seal (14), preferably 1 to 30%, in particular 5% to 25%.

7. Battery pack (2) according to any one of the preceding claims, characterized in that said seal (14) is deposited in a groove (21) formed in the thickness of the housing (4) and / or the cover (8).

8. Battery pack (2) according to the preceding claim, characterized in that the groove (21) for receiving the at least one sealing gasket has a larger section at the weakening zone (18) than that of the rest of the groove (21).

9. Battery pack (2) according to any one of the preceding claims, characterized in that the at least one cover (8) and / or the housing comprises a support zone which is in contact with the at least one seal (14) interposed between this cover (8) and the housing (4), the support zone comprising a relief (19, 20), in particular a groove, capable of cooperating with the at least one seal (14) in its weakened zone (18).

10. Battery pack (2) according to any one of the preceding claims, characterized in that the weakened zone (18) of the at least one seal (14) has a compression rate lower than the compression rate of the rest of the seal (14).

11. Battery pack (2) according to any one of the preceding claims, characterized in that at least two seals (14, 24) are interposed between the housing (4) and the at least one cover (8), on a frame (16) of the housing (4), each seal (14, 24) being radially offset from the adjacent seal in a first radial direction, each seal comprising a weakening zone (18a, 18b), the weakening zone (18a, 18b) arranged in a first seal (14) being in particular angularly offset relative to the weakening zone (18a, 18b) arranged in a second seal (24).

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