Flooding valve for a storage battery

Abstract

The invention relates to a flooding valve (10) for a storage battery, comprising a tubular body (20) which is closed by a seal (30) suitable for breaking when an overpressure is applied to the face thereof that faces the outside of the tubular body. According to the invention, this valve comprises a flap (23) which also closes the tubular body and which is suitable for opening towards the outside of the tubular body when an overpressure is applied to the face thereof that faces the seal.

Description

FLOODING VALVE FOR ACCUMULATOR BATTERY TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates generally to safety devices intended to equip accumulator batteries.

[0002] It relates more particularly to a flooding valve for an accumulator battery, comprising a tubular body which delimits a passage closed by a cover, said cover being adapted to break when an overpressure is exerted on its face facing an external side of the tubular body.

[0003] The invention also relates to a storage battery equipped with such a flooding valve, and to a motor vehicle comprising such a battery. STATE OF THE ART

[0004] An electric or hybrid motor vehicle is generally equipped with an electric motor and a storage battery designed to supply current to the electric motor.

[0005] Such a storage battery comprises an external casing and a large number of electrochemical cells housed in this external casing, each of which is adapted to deliver a low voltage (of a few volts). These electrochemical cells are connected to each other so that the battery can deliver a high voltage (of a few tens to a few hundred volts).

[0006] Under accidental conditions, one of the electrochemical cells in a storage battery may overheat abnormally, causing the surrounding cells to overheat. This is known as thermal runaway. Examples of accidental conditions include a road accident, an act of vandalism, or, very unlikely, an internal failure of the storage battery.

[0007] Above a certain temperature (typically around 100 degrees), exothermic reactions occur in cells and generate gases.

[0008] In order to prevent damage to the structure of the storage battery by the pressure of these gases, it is known to equip the external casing of the battery with a safety valve which allows the gases to escape when the pressure in the casing exceeds a predetermined threshold.

[0009] This solution, however, is not entirely satisfactory since, although it prevents the case from exploding, it does not stop the runaway exothermic reactions and therefore the complete combustion of the accumulator battery.

[0010] However, such a fire of chemical origin turns out to be very violent (it is advisable to stay away from it). much more than a classic car fire). Such a fire is also very difficult to extinguish.

[0011] To extinguish this chemical fire, one solution is to flood the accumulator battery by injecting a fluid such as water into the external casing.

[0012] Document FR3093864 proposes to place a flooding valve in an orifice of the accumulator battery housing. This valve delimits a passage initially closed by a cover which is designed to break under the effect of the pressure of water coming from a firefighter's fire hose.

[0013] This flooding valve thus allows firefighters to flood the storage battery effectively. Its major drawback is that, in certain specific battery configurations, it may not withstand the temperature and pressure conditions that can be found in the battery during runaway exothermic reactions for as long as desired.

[0014] In fact, although the safety valve limits the rise in pressure in the casing, the fact remains that the temperature can, in certain particular battery configurations, increase sharply and destroy the cover of the flooding valve in too short a time (before the firefighters can intervene in particular). PRESENTATION OF THE INVENTION

[0015] In order to overcome the aforementioned drawback of the prior art, the present invention proposes to equip the housing of the accumulator battery with a more heat-resistant flooding valve.

[0016] More particularly, the invention provides a flooding valve as defined in the introduction, further comprising a flap which closes the passage delimited by the tubular body and which is adapted to release at least part of said passage when an overpressure is exerted on its face facing the side of said cover.

[0017] Thus, thanks to the invention, the valve protects the cover as much as possible from the heat resulting from the combustion of the electrochemical cells. The cover can therefore remain protected from high temperatures while the passengers leave the vehicle, and preferably until the fire brigade arrives. In fact, this valve allows the chemical fire to be confined for longer in the external casing of the storage battery.

[0018] The valve is designed to press harder against the tubular body as the pressure increases in the battery case, which helps protect the seal and confine the fire to the external case.

[0019] On the other hand, this valve, mounted tilting, is naturally designed to open when the jet of water from the fire hose pierces the cover and impacts its inner face. It therefore does not hinder water injection.

[0020] In summary, the flooding valve withstands the pressure and heat stresses exerted on it during runaway exothermic reactions in the battery case, but it opens without difficulty under the pressure of a water jet from a fire hose. The objective for the valve is to withstand the heat for at least five minutes after the start of runaway exothermic reactions in the battery.

[0021] Another advantage of the flooding valve is that its simplicity of manufacture and installation helps to limit its overall cost.

[0022] This valve can also be installed on any accumulator battery box.

[0023] Other advantageous and non-limiting characteristics of the flooding valve according to the invention, taken individually or in all technically possible combinations, are the following: - the valve and the cover are located at both ends of the tubular body; - the valve is at least partly mounted to move in tilting on the tubular body between a closed position in which the valve closes said passage and an open position in which the valve releases at least part of said passage; - an elastic return means is provided suitable for returning the valve to the closed position; - the valve comprises two parts of complementary shapes which are each mounted to move in tilting motion on the tubular body between a closed position in which the two parts together close said passage and an open position in which the two parts release at least part of said passage; - then, an elastic return means is adapted to return each part of the valve to the closed position; - said cover is glued onto the tubular body; - said tubular body comprises a flange and a counter-flange adapted to be fixed together through an orifice of a housing of the accumulator battery and to pinch the edge of said orifice; - a sealing gasket is provided sandwiched between the housing and the flange or counter-flange.

[0024] The invention also relates to a storage battery comprising a housing which has an orifice, and a flooding valve as mentioned above, which is engaged through said orifice in such a way that the side of the tubular body which is provided with the valve is turned towards the inside of said battery.

[0025] The invention also relates to a motor vehicle comprising a roof, an electric motor and a storage battery as mentioned above, which is adapted to supply the electric motor with current, and which is oriented such that the valve of drowning is facing the roof.

[0026] Preferably, the motor vehicle having a row of front seats and a row of rear seats, the flooding valve is located under the row of rear seats.

[0027] Of course, the various features, variants and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive. DETAILED DESCRIPTION OF THE INVENTION

[0028] The description which follows with reference to the appended drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be implemented.

[0029] On the attached drawings:

[0030] [Fig. 1] is a schematic view of a motor vehicle equipped with an accumulator battery comprising a housing and a flooding valve according to the invention;

[0031] [Fig. 2] is a schematic cutaway perspective view of the flooding valve of Fig. 1, in the closed configuration;

[0032] [Fig. 3] is a schematic sectional view of the flooding valve of Figure 1, in the closed configuration;

[0033] [Fig. 4] is a counterpart view of Fig. 2, in which the flooding valve is shown in the open configuration;

[0034] [Fig. 5] is a counterpart view of Fig. 3, in which the flooding valve is shown in the open configuration.

[0035] In Figure 1, a motor vehicle 1 is shown. This motor vehicle could be of any type (truck, bus, boat, plane, etc.). This is a car.

[0036] This car typically has a chassis and bodywork components that include a floor and a roof. It also has seats (not visible), here arranged in two rows.

[0037] This car has a hybrid or electric powertrain. This powertrain therefore comprises at least one electric machine (here called electric motor 5) and a storage battery 2 which is electrically connected to the electric motor 5 to supply it with current.

[0038] The storage battery 2 is, in the example shown, fixed under the floor of the motor vehicle. It could be installed elsewhere, but this position is preferred here.

[0039] This accumulator battery 2 conventionally comprises an external casing 3 which houses electrochemical cells.

[0040] In the example shown in the figures, this external housing 3 has a parallelepiped shape. It therefore has four side walls, an upper wall facing the roof of the vehicle and a lower wall facing the opposite way.

[0041] This external housing 3 is fixed to the chassis so as to extend substantially horizontally (when the vehicle is located on a horizontal road).

[0042] As shown in Figure 2, the external housing 3 comprises an orifice 4, here of circular shape around an axis A1, provided to accommodate a flooding valve 10. As will be described below, this flooding valve 10, which is more precisely the subject of the present invention, is specifically provided to allow a firefighter equipped with a fire hose to flood the electrochemical cells in order to prevent them from catching fire or in order to extinguish the fire which is setting them ablaze.

[0043] This orifice 4 could be located in any wall of the external housing 3. However, preferably, it is located in its upper wall. Thus, this orifice 4 faces the roof of the vehicle. More precisely, it is located under a seat in the rear row of the motor vehicle, so as to be visible from outside the vehicle when the seat has burned.

[0044] Of course, especially in the case of a utility vehicle with only one row of seats, the hole could be located elsewhere, and in this example under a front seat.

[0045] This orifice 4 is intended to be hermetically closed during normal use of the motor vehicle, thanks to the flooding valve 10.

[0046] This flooding valve 10 firstly comprises a tubular body 20 which is equipped with means for its attachment to the external housing 3, in the orifice 4.

[0047] This tubular body 20 could be presented in various forms, provided that it can be fixed to the external housing 3 and that it delimits a passage 29 which passes through the orifice 4 and which allows a liquid to be injected from the outside (referenced I in figures 2 and following) towards the inside (referenced II) of the external housing 3.

[0048] Here, this tubular body 20 is made in two separate male and female parts, called flange 21 and counter-flange 22.

[0049] The flange 21 comprises a tube 211 with an external diameter slightly smaller than the diameter of the orifice 4, so as to be able to be engaged through this orifice 4. This tube 211 is bordered, at its end located on the external side I, by an external peripheral rim 210 whose diameter is greater than the diameter of the orifice 4, so as to be able to rest around the edge of this orifice 4.

[0050] This external peripheral rim 210 has a lower face, facing the external housing 3, which is flat so as to be able to be applied to the flat external face of this external housing 3. However, it has a peripheral groove hollowed out in this face. lower and in which is placed a sealing gasket 26 (figures 3 and 5) which is intended to be crushed between the bottom of this groove and the external housing 3, so as to ensure a good seal all around the orifice 4. Thus, the gases present inside the external housing 3 cannot escape between the tube 211 and the edge of the orifice 4.

[0051] The counter-flange 22 is then provided to pull the flange 21 towards the inside II of the housing in order to crush this sealing gasket 26.

[0052] It is presented here in the form of a nut with an external diameter greater than the diameter of the orifice 4, so as to be able to rest around the edge of this orifice 4. It is tapped on its internal face so as to be able to be screwed onto the threaded external face of the tube 211 of the flange 21.

[0053] It extends over a height (along the axis A1) such that once screwed forcibly onto the flange 22, its lower end facing the interior II of the housing 3 protrudes from the free end of the tube 211.

[0054] Thus, as will become more clear below, only the counter-flange 22 will be directly subjected to high temperatures in the event of a chemical fire. It must therefore be made of a highly heat-resistant material. In practice, this could be polyketone, whose melting temperature exceeds 200°C. The flange 21 could be made of a different material. However, here, it will be made of the same material.

[0055] Of course, as a variant, the flanges and counter-flange could be assembled in other ways, for example by gluing, welding, snap-fastening, using a circlip, via a bayonet system, etc.

[0056] Alternatively, the tubular body 20 could be manufactured in a single piece snapped onto the edge of the orifice or welded thereto.

[0057] When the storage battery 2 is operating normally (when no unwanted exothermic reaction occurs in the housing), the passage 29 delimited by the tube 211 should be closed.

[0058] For this purpose, the flooding valve 10 comprises two separate elements.

[0059] It firstly comprises a cover 30 which is designed to completely close this passage 29, on the external side I of the external housing 2.

[0060] This cover 30 is fixed on the tubular body 20, on the external side I.

[0061] It is flame retardant. The objective is that, when it is subjected on the outside I to high temperatures, for example due to a fire spreading in the passenger compartment of the motor vehicle 1, it does not deteriorate and thus prevents the spread of the fire from the outside I to the inside II of the external casing 3 of this battery.

[0062] In practice, it could be formed from a metallic material (for example in the form of a thin metal disc). Here, it is more precisely formed from different layers, including an outer layer of fire-resistant mica-based felt and another, more rigid layer. Here, a layer of polyethylene terephthalate (PET) and acrylic foam is provided.

[0063] The cover 30 is here glued to the upper face of the external peripheral edge 210 of the flange 21, using an adhesive resistant to high heat.

[0064] The objective is for the seal thus bonded to resist 10 minutes at a temperature of 200°C on its external face (and also 10 minutes when the temperature in the housing is 500°C, thanks to the valve described below).

[0065] This cover 30 is intended to prevent any entry of liquid, gas or solid into the accumulator battery 2 as long as it is in good condition.

[0066] However, it is designed to give way when subjected to excess pressure on its upper face.

[0067] Overpressure means a pressure difference between its two faces (external side I and internal side II of the external housing 3) greater than a predetermined threshold.

[0068] Typically, the seal can be designed to yield when the pressure difference between its two faces exceeds several bars, for example 5 bars.

[0069] Thus, when firefighters point a jet of water J 1 from a fire hose towards this cover 30, the latter is designed to give way under the pressure of the water jet (see figures 4 and 5).

[0070] A chemical fire, caused by heating of the electrochemical cells, generates very high temperatures which the cover 30 would not withstand for long. Indeed, the highly exothermic reactions generated by runaway combustion of the electrochemical cells are likely to generate temperatures much higher than those which the cover 30 would experience if the entire motor vehicle 1 caught fire except for the accumulator battery 2.

[0071] At the other end of the tubular body 20, the flooding valve 10 is then equipped with a flap 23 which is designed to protect the cover 30 from heat.

[0072] This valve 23 is articulated on the tubular body 20 around a pivot axis A2 orthogonal to the axis A1.

[0073] It is more precisely articulated on the counter-flange 22. It is designed to close the passage 29 delimited by the tubular body 20 by pressing against the lower end edge 28 of this counter-flange 22. In this position, the more the pressure increases in the external housing 3, the more the valve 23 is compressed against this lower end edge 28.

[0074] In practice, the valve 23 has a disc shape with a lug projecting from its circular edge, by which it is articulated on the counter-flange 22. The latter then has two lugs projecting from its lower end edge 28, which are located on either side of the lug of the valve 23. A cylindrical axis passing through these three lugs then allow the tilting of the valve 23 to be guided between its closed position on the lower end edge 28 of this counter-flange 22 and an open position releasing the passage 29. The angle between these two positions is at least 45° to allow the water jet J1 to penetrate well into the external housing 3.

[0075] Apart from these two lugs, the lower end edge 28 of the counter-flange 22 is substantially flat. However, it has a hollow peripheral groove in which is placed a sealing gasket 25 (figures 3 and 5) designed to be crushed between the bottom of this groove and the valve 23, so as to ensure good sealing when the pressure increases in the external housing 3.

[0076] In practice, the valve 23 will be made of the same material as the counter-flange 22, namely here polyketone, since it will be subjected to the same thermal constraints.

[0077] Preferably, the valve 23 is designed to be automatically returned to the closed position against the lower end edge 28 of the counter-flange 22. An elastic system is used here for this purpose.

[0078] This elastic system is designed so that the valve 23 opens when it experiences an overpressure on its upper face (the one facing the cover 30). By overpressure, we mean a pressure difference between its two faces (outer side I and inner side II of the external housing 3) greater than a predetermined threshold, for example several bars.

[0079] The elastic system comprises, in the example illustrated in the figures, a torsion spring 24 engaged on the cylindrical axis. This torsion spring 24 has sufficient stiffness to return the valve 23 to the closed position and keep it there during normal use of the vehicle, but sufficiently low for the valve 23 to open when a jet of water J1 from a fire hose strikes the valve 23.

[0080] Alternatively, provision could have been made to glue the valve 23 to the lower end edge 28 of the counter-flange 22, the glue used however having to be able to yield easily when a jet of water from a fire hose hits the valve.

[0081] It should be noted here that the external housing 3 will preferably be equipped with a safety valve which allows the evacuation of part of the gases contained in the housing when the pressure prevailing there exceeds a predetermined threshold. Indeed, if the pressure exceeded a rupture threshold, it could damage the external housing 3 or the valve 23 of the flooding valve 10, which is something which we absolutely seek to avoid.

[0082] The present invention is in no way limited to the embodiment described and shown, but those skilled in the art will be able to provide any variation in accordance with the invention.

[0083] Typically, in the embodiment illustrated in the figures, it is understood that a free space must be provided between the flooding valve 10 and the elements housed in the external housing 3 (in particular the electrochemical cells, etc.) so that these the latter do not hinder the opening of the valve 23.

[0084] However, we are trying to provide the thinnest possible external housings. We could then plan to place the flooding valve in a protrusion of the housing that projects upwards. However, this solution is not preferred since we are trying to use housings without protrusions, whose flooding valves project little above the upper surface.

[0085] Then, according to a variant of the invention, it would be possible to use a valve which is not a single-piece valve which, when it opens, describes a large arc of a circle requiring a large clearance inside the housing, but a valve comprising several separate flaps which, when they open, describe arcs of circles of smaller diameters. For example, the valve could comprise two flaps in the form of complementary half-discs, hinged opposite each other on the lower end edge of the counter-flange.

[0086] According to another variant of the invention, the valve and / or the cover could be located, not at the ends of the tubular body, but inside the passage delimited by this tubular body.

[0087] Alternatively, and not preferentially, the valve could be snapped onto the lower end edge of the counter-flange, so that it can be ejected towards the inside of the external housing when a water feature strikes it.

[0088] Similarly, the cover could not be glued but clipped onto the flange.

Claims

CLAIMS

1. Flooding valve (10) for accumulator battery (2), comprising a tubular body (20) which delimits a passage (29) closed by a cover (30), said cover (30) being adapted to break when an overpressure is exerted on its face turned towards an external side of the tubular body (20), characterized in that it comprises a valve (23) which closes said passage (29) and which is adapted to release at least part of said passage (29) when an overpressure is exerted on its face turned towards said cover (30).

2. A flooding valve (10) according to claim 1, wherein the flap (23) and the seal (30) are located at both ends of the tubular body (20).

3. Flooding valve (10) according to claim 1 or 2, in which the flap (23) is at least partly mounted to move in tilting manner on the tubular body. (20) between a closed position in which the valve (23) closes said passage (29) and an open position in which the valve (23) releases at least part of said passage (29), an elastic return means (24) being adapted to return the valve (23) to the closed position.

4. Flooding valve according to claim 3, in which the valve comprises two parts of complementary shapes which are each mounted to move in tilting on the tubular body between a closed position in which the two parts together close said passage and an open position in which the two parts release at least part of said passage, an elastic return means being adapted to return each part of the valve to the closed position.

5. Flooding valve (10) according to one of claims 1 to 4, wherein said cover (30) is glued to the tubular body (20).

6. Flooding valve (10) according to one of claims 1 to 5, wherein said tubular body (20) comprises a flange (21) and a counter-flange (22) adapted to be fixed together through an orifice (4) of a housing (3) of the accumulator battery (2) and to pinch the edge of said orifice (4).

7. Flooding valve (10) according to one of claims 1 to 6, wherein there is provided a seal (26) sandwiched between the housing (3) and the flange (21) or the counter flange (22).

8. A storage battery (2) comprising a housing (3) which has an orifice (4), and a flooding valve (10) which is in accordance with one of claims 1 to 7 and which is engaged through said orifice (4) in such a way that the side of the tubular body (20) which is provided with the valve (23) is turned towards the inside of said battery (2).

9. A motor vehicle (1) comprising a roof, an electric motor (5) and a storage battery (2) which is in accordance with claim 8, which is adapted to supply the electric motor (5) with current, and which is oriented such that the flooding valve (10) faces the roof.

10. A motor vehicle (1) according to claim 9, comprising a front row of seats and a rear row of seats, and wherein the flooding valve (10) is located under the rear row of seats.

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