Flooding valve for rechargeable batteries

Abstract

The invention relates to a flooding valve (10) for a storage battery, comprising a tubular body (20) closed by a spigot (30) adapted to rupture when overpressure is applied to its face facing the outside of the tubular body. According to the invention, this valve includes a flap (23) that also closes the tubular body and is adapted to open outwards from the tubular body when overpressure is applied to its face facing said spigot. Figure 2

Description

Title of the invention: Flooding valve for rechargeable batteries Technical field of the invention

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

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

[0003] The invention also relates to a battery of accumulators equipped with such a flooding valve, and 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 battery of accumulators intended to supply current to the electric motor.

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

[0006] Under accidental conditions, one of the electrochemical cells in the storage battery may overheat and cause neighboring cells to heat up as well. This is known as thermal runaway. Accidental conditions include, for example, a road accident, an act of vandalism, or, in the highly improbable event of an internal failure of the storage battery.

[0007] Beyond a certain temperature (typically, around one hundred degrees), exothermic reactions occur in the cells and generate gases.

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

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

[0010] However, such a fire of chemical origin proves to be very violent (one should keep much further away from it than from a conventional car fire). Such a fire is also very difficult to extinguish.

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

[0012] Document FR3093864 proposes for this purpose placing a flooding valve in an opening in the battery casing. This valve delimits a passage initially closed by a flap which is designed to break under the effect of the pressure of water from a fire hose.

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

[0014] Indeed, although the safety valve limits the pressure rise in the casing, the temperature can, in certain specific battery configurations, rise sharply and destroy the flooding valve seal in too short a time (before the firefighters can intervene in particular). Presentation of the invention

[0015] In order to remedy the aforementioned drawback of the prior art, the present invention proposes to equip the battery casing with a flooding valve that is more resistant to heat.

[0016] More particularly, the invention proposes 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 turned towards said operculum.

[0017] Thus, thanks to the invention, the valve protects the cover as much as possible from the heat generated by the combustion of the electrochemical cells. The cover can therefore remain protected from high temperatures while the passengers exit the vehicle, and preferably until the fire department arrives. Indeed, this valve allows the chemical fire to be contained for a longer period within the external casing of the battery.

[0018] The valve is designed to apply itself more firmly against the tubular body as the pressure increases in the battery casing, which contributes to the protection of the seal and to the containment of the fire in the external casing.

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

[0020] In summary, the flooding valve withstands the pressure and heat stresses exerted on it during the runaway exothermic reactions in the battery casing, but it opens easily 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 the 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 battery case.

[0023] Other advantageous and non-limiting features of the flooding valve In accordance with the invention, taken individually or in all technically possible combinations, are as follows: - the valve and the operculum are located at the two ends of the tubular body; - the valve is at least partly mounted to pivot 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 mechanism is provided to return the valve to the closed position; - the valve comprises two parts of complementary shapes which are each mounted movably by 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 a part of said passage; - then, an elastic return mechanism is suitable for returning each part of the valve to the closed position; - said operculum is glued onto the tubular body; - said tubular body includes a flange and a counter-flange adapted to be fixed together through an opening in a battery casing and to pinch the edge of said opening; - a sealing gasket is provided, sandwiched between the housing and the flange or counter-flange.

[0024] The invention also relates to a battery of accumulators comprising a casing which has an orifice, and a flooding valve as described above, which is engaged at through said orifice in such a way that the side of the tubular body which is fitted 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 battery of accumulators as above, which is adapted to supply the electric motor with current, and which is oriented such that the flooding valve is turned towards the roof.

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

[0027] Of course, the various features, variants, and embodiments of the invention can be combined with one another in various ways, provided they are not incompatible or mutually exclusive. Detailed description of the invention

[0028] The following description with regard to the attached drawings, given by way of non-limiting examples, will make it clear what the invention consists of and how it can be carried out.

[0029] On the attached drawings:

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

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

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

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

[0034] [Fig.5] is a homologous view of [Fig.3], on which the drowning valve is shown in the open configuration.

[0035] Figure 1 shows a motor vehicle 1. This motor vehicle could be of any type (truck, bus, boat, airplane, etc.). Here, it is a car.

[0036] This car conventionally comprises a chassis and bodywork elements which notably form a floor and a roof. It also includes seats (not visible), here arranged in two rows.

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

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

[0039] This battery of accumulators 2 conventionally comprises an external case 3 which houses electrochemical cells.

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

[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 [Fig.2], the external housing 3 has an orifice 4, here circular in shape around an axis Al, intended to accommodate a flooding valve 10. As will be described later, this flooding valve 10, which is more precisely the subject of the present invention, is specifically intended to allow a firefighter equipped with a fire hose to flood the electrochemical cells in order to prevent them from catching fire or to extinguish the fire that is igniting them.

[0043] This opening 4 could be located in any wall of the external housing 3. However, preferably, it is located in its upper wall. Thus, this opening 4 is oriented towards 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, particularly in the case of a utility vehicle with only one row of seats, the opening may be located elsewhere, and in this example under a front seat.

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

[0046] This flooding valve 10 first of all 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 in various forms, provided that it can be attached 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) to the inside (referenced II) of the external housing 3.

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

[0049] The flange 21 includes a tube 211 with an outside diameter slightly smaller than the diameter of the orifice 4, so that it can be inserted through this orifice 4. This tube 211 is edged, at its end located on the outside side I, by a rim external peripheral 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 apply itself to the flat external face of this external housing 3. However, it has a recessed peripheral groove in this lower face in which a sealing gasket 26 (Figures 3 and 5) is placed, which is designed to be compressed 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 intended 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 outer 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 inner face so as to be able to screw onto the threaded outer face of the tube 211 of the flange 21.

[0053] It extends over a height (along the axis Al) such that once screwed tightly onto the flange 22, its lower end turned towards the inside II of the housing 3 protrudes from the free end of the tube 211.

[0054] Thus, as will become clearer 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 material highly resistant to heat. In practice, this could be polyketone, which has a melting point exceeding 200°C. The flange 21 could be made of a different material. However, in this case, it will be made of the same material.

[0055] Of course, alternatively, the flanges and counter-flange could be assembled differently, for example by gluing, welding, snap-fitting, using a circlip, via a bayonet system...

[0056] As an alternative, the tubular body 20 could be made of a single piece snapped onto the edge of the orifice or welded to it.

[0057] When the battery accumulator 2 is functioning 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 distinct elements.

[0059] It includes first of all a lid 30 which is intended to completely close this passage 29, on the outside side I of the external housing 2.

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

[0061] It is fireproof. 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 degrade 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 made of a metallic material (for example, in the form of a thin metal disc). Here, it is more precisely formed of 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 an acrylic foam are provided.

[0063] The operculum 30 is here glued to the upper face of the external peripheral rim 210 of the flange 21, using a heat-resistant adhesive.

[0064] The objective is for the lid thus glued to withstand 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 flap described below).

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

[0066] On the other hand, it is designed to give way when subjected to overpressure on the side of its upper face.

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

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

[0069] Thus, when firefighters point a jet of water J1 from a fire hose towards this opening 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 the overheating of the electrochemical cells, generates very high temperatures which the lid 30 would not withstand for long. Indeed, the highly exothermic reactions generated by a runaway combustion of the electrochemical cells are likely to generate temperatures far exceeding those that the lid 30 would experience if the entire motor vehicle 1 caught fire except for the battery 2.

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

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

[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 bearing against the lower end edge 28 of this counter-flange 22. In this position, the more the pressure increases in the external housing 3, plus the flap 23 is compressed against this lower end edge 28.

[0074] In practice, the valve 23 has a disc shape with a protruding lug on its circular edge, by which it is articulated on the counter flange 22. The latter has two protruding lugs on 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 guides the tilting of the valve 23 between its closed position on the lower end edge 28 of this counter flange 22 and an open position freeing the passage 29. The angle between these two positions is at least 45° to allow the water jet J1 to penetrate the external housing 3 effectively.

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

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

[0077] Preferably, the flap 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 is subjected to overpressure on the side of its upper face (the side facing the operculum 30). Overpressure is understood to mean a pressure difference between its two faces (outer side I and inner side II of the external housing 3) exceeding a predetermined threshold, for example several bars.

[0079] The elastic system in the example illustrated in the figures comprises 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 maintain it there during normal use of the vehicle, but is low enough that the valve 23 opens when a jet of water J1 from a fire hose strikes the valve 23.

[0080] Alternatively, it could have been provided that the flap 23 be glued to the lower end edge 28 of the counter flange 22, the glue used however having to be able to give way easily when a jet of water from a fire hose hits the flap.

[0081] It should be noted here that the external housing 3 will preferably be equipped with a safety valve that allows the evacuation of some of the gases contained in the housing when the pressure inside exceeds a predetermined threshold. Indeed, if the pressure were to exceed a rupture threshold, it could damage the external housing 3 or the valve 23 of the flooding valve 10, which is something that must be avoided at all costs.

[0082] The present invention is in no way limited to the embodiment described and represented, but a person skilled in the art will be able to make 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 casing 3 (in particular the electrochemical cells...) so that the latter do not obstruct the opening of the valve 23.

[0084] The aim is to design the thinnest possible external housings. One could then consider placing the flooding valve in an upward-protruding protrusion of the housing. However, this solution is not preferred since the goal is to use housings without protrusions, where the flooding valves protrude only slightly above the upper surface.

[0085] Thus, according to one embodiment of the invention, it would be possible to use a valve that is not a single piece 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 shape of complementary half-disks, 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 operculum could be located, not at the ends of the tubular body, but inside the passage delimited by this tubular body.

[0087] As a further alternative, and in a non-preferential manner, the flap could be snapped onto the lower end edge of the counter flange, so that it can be ejected into the outer casing when a jet of water strikes it.

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

Claims

Demands

1. Flooding valve (10) for accumulator battery (2), comprising a tubular body (20) which delimits a passage (29) closed by a operculum (30), said operculum (30) being adapted to break when an overpressure is exerted on its face turned towards an outside 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 a part of said passage (29) when an overpressure is exerted on its face turned towards said operculum (30).

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

3. Flooding valve (10) according to claim 1 or 2, wherein the valve (23) is at least partly mounted movably in a tilting motion 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 a part of said passage (29), an elastic return means (24) being adapted to return the valve (23) to the closed position.

4. A flooding valve according to claim 3, wherein the valve comprises two parts of complementary shapes, each of which is mounted movably in a tilting manner 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 a 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 any one of claims 1 to 4, wherein said operculum (30) is glued onto the tubular body (20).

6. Flooding valve (10) according to any 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 claim 6, wherein a sealing gasket (26) is provided sandwiched between the housing (3) and the flange (21) or counter-flange (22).

8. Accumulator battery (2) comprising a casing (3) which has an orifice (4), and a flooding valve (10) which conforms to any one of claims 1 to 7 and which is engaged through said orifice (4) such that the side of the tubular body (20) which is provided with the valve (23) is turned towards the interior of said battery (2).

9. Motor vehicle (1) comprising a roof, an electric motor (5) and a battery of accumulators (2) which conforms to claim 8, which is adapted to supply the electric motor (5) with current, and which is oriented such that the flooding valve (10) is turned towards the roof.

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

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