Energy storage device for a vehicle comprising two tanks

Abstract

Energy storage device for a vehicle comprising two tanks Energy storage device (2) for a motor vehicle (1), comprising a first tank (3) intended to store an energy fluid and a second tank (4) intended to store said energy fluid, the second tank being fixed to the first tank. Figure for abstract: figure 2

Description

Title of the invention: Energy storage device for a vehicle comprising two tanks Technical field of the invention

[0001] The invention relates to an energy storage device for a vehicle intended to store an energy fluid, in particular hydrogen. The invention also relates to a vehicle, in particular a motor vehicle, comprising such an energy storage device. State of the prior art

[0002] In order to make the use of vehicles less polluting, vehicles are known that are equipped with a fuel cell powered by hydrogen. These vehicles therefore have a tank in which hydrogen is stored before being consumed by the fuel cell. The fuel cell provides electrical energy that can be consumed directly by an electric motor to move the vehicle forward, or stored in an electrochemical battery on board the vehicle.

[0003] The pressure of the hydrogen in the tank can be very high, for example of the order of 700 Bar. The tank must therefore be particularly resistant to the mechanical stresses exerted by pressurized hydrogen. In addition, hydrogen is a highly flammable gas which causes fire risks in the event of a leak. Hydrogen tanks must therefore also be shock-resistant, so as to guarantee the safety of passengers in the event of a vehicle accident. Tanks known from the state of the art generally take the form of one or more cylinders on board the vehicle. Such cylinders are particularly bulky and complex to integrate within the vehicle.

[0004] On the other hand, the autonomy of such a vehicle is limited by the quantity of hydrogen that the tank is capable of storing. To increase the autonomy of a vehicle, the volume of each cylinder is increased or the number of cylinders on board is increased. However, such arrangements are very bulky and penalize the volume available for transporting passengers and / or cargo.

[0005] Thus, the vehicles known from the state of the art present a poor compromise between autonomy, space available for passengers or for loading objects, and size of the vehicle. Presentation of the invention

[0006] The aim of the invention is to provide an energy storage device for a vehicle which overcomes the above drawbacks and improves the energy storage devices. energy storage known from the prior art.

[0007] More specifically, a first object of the invention is to provide an energy storage device intended to store an energy fluid which is compact, which allows a large quantity of energy fluid to be stored, and which is easy to manufacture. Summary of the invention

[0008] The invention relates to an energy storage device for a motor vehicle, comprising a first tank intended to store an energy fluid and a second tank intended to store said energy fluid, the second tank being fixed to the first tank.

[0009] The first tank may comprise a wall bearing directly against a wall of the second tank, in particular the first tank may comprise a flat wall bearing directly against a flat wall of the second tank.

[0010] The first tank and the second tank may each comprise a rigid structure made of a composite material.

[0011] The second reservoir may comprise a shape symmetrical to the shape of the first reservoir.

[0012] The first reservoir may comprise at least a first pair of opposing walls connected to each other by a first set of connecting elements, passing through the first reservoir and extending parallel to a first axis, and the second reservoir may comprise at least a first pair of opposing walls connected to each other by a first set of connecting elements, passing through the second reservoir and extending parallel to the first axis.

[0013] The connecting elements of the first tank and the connecting elements of the second tank may be hollow, each connecting element of the second tank extending opposite a connecting element of the first tank, the second tank being fixed to the first tank by a set of fixing means, in particular a set of fixing screws, each fixing means passing through a connecting element of the first tank and / or a connecting element of the second tank.

[0014] The set of fixing means may comprise a first set of fixing screws and a second set of fixing screws, each fixing screw of the first set of fixing screws passing through a connecting element of the first tank, each fixing screw of the second set of fixing screws passing through a connecting elements of the second tank, and the energy storage device may comprise a set of nuts, each nut cooperating with a fixing screw of the first set of fixing screws and a fixing screw of the second set of screws fixing to fix the second tank to the first tank.

[0015] The connecting elements of the first tank through which the first set of fixing screws pass may each comprise a flare, and / or the connecting elements of the second tank through which the second set of fixing screws pass may each comprise a flare, each nut being housed in a flare of a connecting element of the first tank and / or in a flare of a connecting element of the second tank.

[0016] The invention also relates to an arrangement for a motor vehicle comprising a left side member, a right side member and an energy storage device as defined previously, the left side member being fixed to the first energy storage device and the right side member being fixed to the second energy storage device.

[0017] The invention also relates to a vehicle, in particular a motor vehicle, comprising an energy storage device as defined above. Presentation of figures

[0018] These objects, characteristics and advantages of the present invention will be explained in detail in the following description of a particular embodiment made without limitation in relation to the attached figures among which:

[0019] [Fig.l] is a schematic top view of a motor vehicle equipped with an energy storage device according to one embodiment of the invention.

[0020] [Fig.2] is a perspective and bottom view of the energy storage device.

[0021] [Fig. 3] is a partial perspective view of a first reservoir of the device energy storage.

[0022] [Fig.4] is a partial and transparent view of the first reservoir of the energy storage device.

[0023] [Fig.5] is a sectional view of a connecting element of the first tank.

[0024] [Fig.6] is a sectional view of a portion of the first tank and the second tank, the first tank being fixed to the second tank by fixing screws and a nut.

[0025] [Fig.7] is a sectional view of a portion of the fixing screws and nut used to secure the first tank to the second tank. Detailed description

[0026] [Fig.l] schematically illustrates a motor vehicle 1 according to one embodiment of the invention. The vehicle 1 may be, for example, a private vehicle or a utility vehicle. Alternatively, it could be a truck, a bus, a lifting machine, an agricultural machine or even any other type of land vehicle. The invention may also be adapted to an aircraft or a boat.

[0027] In this document, the X axis designates the longitudinal axis of the vehicle 1. When moving forward and in a straight line, the vehicle 1 moves from the rear to the front in a direction parallel to its longitudinal axis. The X axis is oriented from the front to the rear of the vehicle, that is to say in the direction of reverse travel. The Y axis designates the transverse axis of the vehicle. The Y axis is oriented from left to right, left and right being defined according to the point of view of a driver of the vehicle 1. The Z axis designates the axis perpendicular to the X axis and the Y axis. It is considered that the vehicle 1 is resting on horizontal ground. The Z axis is a vertical axis, oriented from bottom to top. The X, Y and Z axes form an orthogonal reference frame. This reference defined in relation to the vehicle 1 may be used to describe an energy storage device 2 of the vehicle 1, even considered outside the vehicle, since the tank is intended to be integrated into the vehicle in a particular orientation..

[0028] The vehicle 1 is equipped with an energy storage device 2 according to one embodiment of the invention. The energy storage device 2 comprises a first tank 3 and a second tank 4 separate from the first tank 3. The first tank 3 and the second tank 4 are intended to store the same energy fluid, and in particular hydrogen. The vehicle 1 also comprises a fuel cell 5 capable of transforming hydrogen into an electric current, and an electric motor 6 powered by an electric current from the fuel cell 5. The electric motor 6 is configured to drive drive wheels of the vehicle 1. The vehicle 1 further comprises a chassis supporting, among other things, the energy storage device 2, the fuel cell 5 and the electric motor 6.

[0029] According to the illustrated embodiment, the energy storage device 2 is therefore intended to store hydrogen or more precisely dihydrogen. According to other variants, the energy storage device 2 could be configured to store other forms of energy gases, for example liquefied petroleum gas or natural gas. The energy storage device could even be intended to store a liquid fuel such as gasoline, diesel or even ethanol. In such a hypothesis, the vehicle could comprise a combustion engine capable of transforming the energy of the energy fluid into electromotive force.

[0030] Generally speaking, the tanks 3 and 4 are intended to contain an energy fluid, that is to say a fluid forming a reserve of fluid energy, convertible into an electromotive force capable of moving the vehicle. Each tank 3, 4 is therefore a component of the vehicle 1 which gives it a certain autonomy. Each tank 3, 4 comprises in particular an inlet opening allowing the tank to be filled with an energy fluid and an outlet opening for delivering and then consuming the energy fluid contained in the tank.

[0031] Tanks 3 and 4 are intended to store the pressurized energy fluid, that is to say at a pressure strictly higher than atmospheric pressure. In this case, the tanks 3 and 4 are intended to store the energy fluid at a pressure greater than or equal to 700 Bar. Alternatively, the tanks could be intended to store the energy fluid at a different pressure, for example a pressure greater than or equal to 300 Bar, or 500 Bar, or 1000 Bar, or any other value. Each tank 3, 4 thus comprises a rigid structure capable of withstanding the forces exerted by the pressurized fluid that it contains, that is to say centrifugal forces acting from inside each tank 3, 4 and which tend to cause it to burst.

[0032] Furthermore, each tank 3, 4 may have a capacity greater than or equal to 20 liters, preferably greater than or equal to 50 liters, or even greater than or equal to 100 liters. A 100-liter tank can store approximately 4 kg of hydrogen at 700 Bar, which gives a motor vehicle a range of around 300 km.

[0033] The structure of each tank 3, 4 is also capable of withstanding significant impacts, in particular impacts occurring in the event of an accident of the vehicle 1, without generating any leakage of the energy fluid to the outside. Accident data and / or simulations and / or crash tests make it possible to size the structure, in particular the required wall thicknesses, so that no leakage of energy fluid occurs, even for the most violent accidents.

[0034] Advantageously, each tank 3, 4, the high strength of which is necessary to withstand high pressures of the energy fluid it contains, as well as to guarantee the safety of the passengers of the vehicle 1 in the event of an accident, can be used to stiffen the structure of the vehicle. Each tank 3, 4 is capable of supporting the weight exerted by other equipment of the vehicle, and also provides a support for fixing this equipment.

[0035] Each tank 3, 4 is capable of supporting loads that can reach at least one hundred kilograms, or even several hundred kilograms. These loads can be static loads such as those exerted by the weight of equipment such as vehicle seats and / or the weight of the vehicle passengers. These loads can also be dynamic loads such as those that appear in particular situations such as during an impact against the vehicle. These different static or dynamic loads can exert compressive or shear forces on each tank 3, 4. These forces are therefore oriented in a different direction from the centrifugal forces exerted by the pressurized energy fluid inside each tank 3, 4.Advantageously, the resistance of each reservoir 3, 4 necessary to resist the pressure exerted by the energy fluid which it contains is therefore also used to support loads which are exerted in different directions.

[0036] Each tank 3, 4 is typically a polymorphic structural tank made of composite materials using a weaving process similar to that presented in document FR 2 888 915 A1. Each tank 3, 4 may comprise internal reinforcement wells which pass through the interior volume of the tank and which connect two by two of the opposite walls of the tank so as to secure them together. This structure and this arrangement ensure mechanical support of each tank suitable for receiving high-pressure gases, in particular for containing hydrogen. Each tank 3, 4 being rigid, it can therefore be used as a structural element of the vehicle, in addition to the conventional structural elements of the underbody of the vehicle.

[0037] The tanks 3 and 4 are arranged in the rear part of the vehicle 1, in particular at the level of a rear part of a base of the vehicle. The tanks 3 and 4 extend in particular under a row of rear seats of the vehicle and / or under a trunk of the vehicle, or even up to the level of a rear bumper of the vehicle. The tanks 3 and 4 can thus be intended to support the load exerted by the rear seats and all of the objects stored in the trunk of the vehicle.

[0038] According to one embodiment, the second tank 4 comprises a shape symmetrical to the shape of the first tank. In particular, the second tank 4 comprises a shape obtained by symmetry of the shape of the first tank 3 with respect to a median plane P extending parallel to the longitudinal axis X and to the vertical axis Z. The median plane P passes through a center of the vehicle along the transverse axis Y. The design and manufacture of the second tank and / or of the interfaces cooperating with the second tank is thus facilitated when the first tank and / or interfaces cooperating with the first tank are already available. According to an alternative embodiment, the second tank could have a shape identical to the shape of the first tank.

[0039] The first tank 3 is positioned on the left side of the vehicle and the second tank 4 is positioned on the right side. Alternatively, this configuration could be reversed. The terms “first” and “second” used in the present description only serve to distinguish the two tanks 3 and 4 from each other and do not in themselves confer any particular characteristic on said tanks.

[0040] The two tanks 3 and 4 are positioned next to each other. The two tanks 3 and 4 are even in direct contact with each other. The first tank 3 comprises a right lateral face, parallel to the X and Z axes, resting against a left lateral face, also parallel to the X and Z axes, of the second tank. The right lateral face of the first tank 3 and the left lateral face of the second tank 4 are planar faces. The two tanks 3 and 4 are therefore in surface contact, as opposed to linear or point contact. No structural element of the vehicle, in particular, no element of a vehicle body is interposed between the two tanks 3 and 4.

[0041] According to the embodiment presented, the contact surface between the two reservoirs extends parallel to the longitudinal axis X and to the vertical axis Z. According to alternative embodiments of the invention, the contact surface between the two reservoirs could extend parallel to the transverse axis Y and to the vertical axis Z, or parallel to the transverse axis Y and to the longitudinal axis X. According to still other variants, the contact surface between the two reservoirs could be non-planar. The contact surface could for example comprise a stepped shape and / or a curved shape.

[0042] An advantage of providing a contact surface between the first reservoir and the second reservoir lies firstly in the fact of not losing any free space between the two reservoirs. The volume available for fixing the energy storage device 2 is therefore fully exploited. In addition, the rigidity of one reservoir reinforces the rigidity of the other reservoir to form a more robust assembly. According to one embodiment, the wall or walls of a reservoir in contact with the other reservoir could be thinned without penalizing the strength of the energy storage device 2 because the thinned wall would be supported by the wall of the other reservoir, itself potentially also thinned.

[0043] The two tanks 3 and 4 are also fixed to each other. The rigidity of the first tank 3 is thus advantageously used to hold the second tank 4, and vice versa. The two tanks 3 and 4 thus form a single-piece assembly which can be mounted as such in the vehicle 1. It is thus possible to simplify the fixing of the two tanks compared to a solution where each tank would be fixed independently of the other to a structure of the vehicle.

[0044] To manufacture a vehicle 1 provided with an energy storage device according to the invention, the two tanks can first be fixed to each other to form the energy storage device 2, then the energy storage device 2 obtained can be fixed to the chassis of the vehicle.

[0045] The tanks 3 and 4 can be isolated from the passenger compartment by a simple protective element, for example made of plastic, which covers their upper face. No structural element must be integrated between the tanks 3 and 4 and the vehicle seats above the tank since the latter have sufficient strength to support the weight of the seats and the passengers seated on these seats.

[0046] Advantageously, the structure of each tank 3 and 4 is made of composite material. Such a material is lighter than steel and even than any other metal for equivalent strength. In addition, the methods for manufacturing components made of composite material make it possible to produce structures with a wide variety of geometric shapes. Structural shapes more complex than those obtained in metal can thus be considered in order to exploit all available volume of the vehicle and thus increase the capacity of the tank. More complex tank shapes can in particular be recommended when the tanks are intended to store a pressurized gas rather than a liquid because, unlike a liquid, the gas does not present a risk of retention in the tank.

[0047] The composite material may comprise a draped or preformed structure, and / or woven and / or braided materials impregnated with resin. The composite material may be formed from reinforcing elements and a matrix. The reinforcing elements may comprise carbon or glass fibers, which are lightweight materials, or Kevlar (registered trademark) which has greater impact resistance. The matrix may be an organic matrix, for example epoxy resin, phenolic resin or a modified polyester. The matrix may also be a metal matrix.

[0048] According to the embodiment presented, the energy storage device 2 comprises two and only two juxtaposed tanks. According to other alternative embodiments of the invention, the energy storage device could comprise a greater number of juxtaposed tanks, for example three, four, five, six or even more juxtaposed tanks. One advantage of using at least two juxtaposed tanks instead of a single tank of equivalent size to all the juxtaposed tanks is to simplify the manufacture of the tanks. Indeed, a large tank requires very large industrial means to be able to be mass-produced. Its manufacture is therefore particularly complex and expensive.This is particularly true when the tanks are made of composite materials because the manufacture of tanks with such materials requires passing blanks of these tanks through specific manufacturing tunnels. The use of several tanks, each of smaller dimensions, advantageously makes it possible to reduce the size of the manufacturing tunnels necessary to manufacture tanks from composite material.

[0049] [Fig.2] illustrates an embodiment of the energy storage device 2. The energy storage device 2 extends across the entire width of the vehicle 1 and is fixed between a left side member 5G and a right side member 5D of the vehicle. The energy storage device 2 further supports a rear impact cross member 6, a left rear wheel hub support 7G and a right rear wheel hub support 7D of the vehicle. The rear impact cross member 6 is connected to a rear face of the energy storage device 2 via a set of columns 8, in particular three columns 8, fixed to the same plate 15. The rear wheel hub supports 7G and 7D are connected to lateral faces of the energy storage device 2 via a set of rods 9G, 9D. The side members 5G and 5D do not do not extend to the rear impact crossmember 6. Thanks to its significant strength, the energy storage device 2 forms a connecting means between the rear impact crossmember 6 and the side members 5G and 5D. Similarly, the energy storage device 2 forms a connecting means between the rear wheel hub supports 7G and 7D on the one hand, and the side members 5G and 5D on the other hand.

[0050] The first tank 3 will now be described in more detail, knowing that the second tank 4 is designed symmetrically to the first tank. The characteristics of the first tank 3 described below are reproduced by the second tank 4.

[0051] In this exemplary embodiment, the first tank 3 typically comprises a roughly parallelepiped shape. It comprises three pairs of opposite walls. A first pair of opposite walls is composed of a front wall 10A and a rear wall 10B. The walls 10A and 10B extend substantially parallel to the Y and Z axes. A second pair of opposite walls is composed of a left side wall 11A and a right side wall 11B. The walls 11A and 11B extend substantially parallel to the X and Z axes. A third pair of opposite walls is composed of an upper wall 12A and a lower wall 12B. The walls 12A and 12B extend substantially parallel to the X and Y axes. Alternatively, any other shape of the tank could be envisaged.

[0052] The first tank 3 bears against the second tank 4 via its right side wall 1 IB. The right side wall 1 IB is flat and generally comprises a rectangular shape. This wall extends over the entire length of the first tank 3 along the X axis and over the entire height of the first tank 3 along the Z axis. The second tank 4 being designed symmetrically to the first tank 3, it comprises a left side wall bearing against the right side wall 1 IB of the first tank 3.

[0053] The first tank 3 also comprises a housing 13 opening onto the lower wall 12B and onto the right side wall 11B. The housing 13 accommodates in particular the rods 9G, which extend substantially parallel to the transverse axis Y from a vertical face of the housing 13. In particular, one end of each of the two rods 9G is fixed to an L-shaped plate 14. This plate 14 is itself fixed against a vertical face and a horizontal face of the housing 13.

[0054] The upper wall 12A may comprise a recess intended to receive the seat base of the vehicle, so that the passengers seated on these seats are not installed too high. Advantageously, the upper wall 12A may also comprise an anti-submarining device. Such a device forms a stop preventing the seat base above the first tank 3 from sliding forward in the event of an accident. The anti-submarining device may be formed by a protrusion extending forward and upward in front of the recess. The anti-submarining device marination may include a profiled shape along the Y axis and / or extend across the entire width of the tank 3 along the Y axis. In addition to improving passenger safety, the integration of the anti-submarining device into the tank makes it possible to increase the volume of the tank and therefore increase its energy fluid storage capacity.

[0055] Figures 3 and 4 illustrate in perspective view the structure of the first tank 3. The walls 10A and 10B are connected to each other by a first set of connecting elements 51 extending parallel to the X axis. These connecting elements form internal wells passing through the interior volume of the tank and securing two opposite walls to each other and working essentially in traction so as to stiffen the structure of the tank. Similarly, the walls 11A and 11B are connected to each other by a second set of connecting elements 52 extending parallel to the Y axis, and the walls 12A and 12B are connected to each other by a third set of connecting elements 53 extending parallel to the Z axis.

[0056] According to an alternative embodiment, the first tank 3 could comprise only one set of connecting elements or only two sets of connecting elements among the three sets of connecting elements 51, 52, 53. Alternatively, all or some of the sets of connecting elements 51, 52, 53 could extend in directions different from the X, Y and Z axes, provided that the axis along which each of the sets of connecting elements extends forms a non-zero angle with the axis along which the other sets of connecting elements extend. Advantageously, the three axes along which the three sets of connecting elements 51, 52 and 53 extend are perpendicular to each other so as to stiffen the tank optimally.

[0057] The connecting elements 51, 52, 53 pass through the first tank 3 from one side to the other between two opposite walls. The connecting elements act as tie rods reinforcing the resistance of the tank: they are subjected to tensile stress when the energy fluid contained in the tank exerts pressure on the walls 10A, 10B, 11A, 11B, 12A, 12B. The connecting elements 51, 52, 53 are arranged inside the casing of the tank 3 and not on the periphery of this casing.

[0058] Preferably, each connecting element 51, 52, 53 is distinct from the other connecting elements, that is to say that the connecting elements 51, 52, 53 are without contact with each other and do not touch each other inside the first reservoir 3. Thus, the reservoir is not compartmentalized and the energy fluid can circulate easily inside the reservoir.

[0059] The connecting elements 51, 52, 53 are hollow. In particular, the connecting elements, which could also be called "reinforcement wells", may be tubes when they have a circular section. However, the section of the connecting elements is not necessarily circular. For example, the section of the connecting elements could also be square, rectangular, polygonal or ovoid.

[0060] [Fig. 5] illustrates in more detail a connecting element 51, the other connecting elements being designed in a similar manner. Each connecting element 51, 52, 53 comprises a tubular shape provided with an external face 54 and an internal face 55. The external face 54 is turned towards the inside of the first reservoir 3 and is therefore intended to be in contact with the energy fluid, while the internal face 55 communicates with the outside of the reservoir and is likely to be in contact with the ambient air.

[0061] The connecting elements 51, 52, 53 may be made of composite material or metal. They may also comprise both a composite material and metal. In particular, they may comprise a metal tube arranged inside a structure made of composite material.

[0062] The internal face 55 may be provided in a material different from that forming the structure of the first tank 3. The internal face 55 may in particular be equipped with a metal tube which extends over the entire length of the connecting element 51, 52, 53 or only at the ends of the connecting elements 51, 52, 53. The metal tube may optionally be ringed on its external periphery so as to guarantee good support in the structure.

[0063] Each connecting element 51, 52, 53 comprises two opposite ends at the level of the two opposite walls that it connects. Due to the hollow nature of the connecting elements 51, 52, 53, the first reservoir 3 comprises, for each connecting element, an opening 56 passing right through the reservoir. These openings 56 do not communicate with the energy fluid storage volume. These openings 56 are therefore not useful for delivering an energy fluid, in particular for delivering pressurized hydrogen to the fuel cell 5.

[0064] On the other hand, the openings 56 can be used for the passage of electrical wires and / or for circulating a liquid. It is thus possible to save the space provided outside the first tank for the passage of electrical wires and / or for hydraulic conduits while providing them with a means of holding them in position.

[0065] The openings 56 can also be used to fix different pieces of equipment of the vehicle. For this purpose, the tank 3 can comprise a set of fixing interfaces 57, each arranged at one end of at least one connecting element 51, 52, 53, in particular arranged in one end of an opening 56. As illustrated in [Fig. 5], all or part of the fixing interfaces 57 can comprise an insert intended to cooperate with a fixing screw 58, for example a fixing screw of type M8 or M10. The insert can be formed in the metal tube equipping the internal face 55 of the connecting elements or be an additional element fitted against the internal face 55 of the connecting elements, for example a plastic dowel. The insert can for example comprise a length of between 20 mm and 60 mm inclusive. The insert can be tapped or untapped. The insert thus provides a means of fixing extending deep into the volume of the tank. Such a means of fixing is particularly robust and allows the fixing of heavy loads to be considered.

[0066] Each fixing interface 57 makes it possible to fix a piece of equipment of the vehicle against a wall of the tank 3. Advantageously, such fixing interfaces 57 can be provided at the ends of each opening 56 of the tank 3. Each connecting element 51, 52, 53 can thus support two fixing interfaces 57 arranged on two opposite faces of the tank. The tank can thus be provided with a multitude of fixing interfaces 57 making it possible to fix various pieces of equipment in very varied positions. The same tank 3 can also be easily reused for different vehicle models because the multitude of fixing interfaces provides numerous possibilities for fixing pieces of equipment. In particular, the plates 14 and 15 as well as the side member 5G can be fixed to the first tank 3 via these fixing interfaces 57.

[0067] Advantageously, the connecting elements 51, 52, 53 are distributed at a regular pitch, for example a pitch between 5 cm and 30 cm inclusive, in particular between 10 cm and 20 cm inclusive. Consequently, the fixing interfaces 57 are distributed on the walls of the tank at a regular pitch. The fixing interfaces 57 are thus arranged according to a grid on the surface of the tank 3. This further facilitates the reuse of the same tank and the same equipment for different vehicle models because this same equipment can be fixed in several places on the tank without requiring an adaptation part. The tank thus forms a modular structure, on which numerous pieces of equipment can be fixed. The invention therefore makes it possible to envisage great freedom of design of motor vehicles while achieving economies of scale.Due to the presence of the housing 13 which locally reduces the volume of the first reservoir 13, certain connecting elements may be shortened or interrupted.

[0068] The second tank 4 also comprises connecting elements as described previously. In particular, the second tank 4 comprises a set of connecting elements 62 extending parallel to the transverse axis Y and connecting a left side wall to a right side wall of the second tank. At least a portion of the connecting elements 62, or even each connecting element 62, extends opposite a connecting element 52.

[0069] Advantageously, and as illustrated in [Fig. 6], the second tank 4 is fixed to the first tank 3 by a set of fixing means passing through connecting elements 52 of the first tank and / or passing through connecting elements 62 of the second tank.

[0070] In particular, as illustrated in [Fig.6], said set of fixing means comprises a first set of fixing screws 71 and a second set of fixing screws 81. Each fixing screw 71 passes through a connecting element 52 of the first tank 3. Each fixing screw 71 comprises a screw head 72 bearing directly or indirectly against a first lateral face of the first tank 3 and a body extending through the opening 56 of a connecting element 52 towards the second tank. Similarly, each fixing screw 81 of the second set of fixing screws passes through a connecting element 62 of the second tank 4. Each fixing screw 81 also comprises a screw head 82 bearing directly or indirectly against a first lateral face of the second tank and a body extending through the opening 56 of a connecting element 62 towards the first tank. There are as many fixing screws 71 as there are fixing screws 81 and each fixing screw 71 extends opposite a fixing screw 81.The body of each fixing screw comprises a length substantially equal to the length of the connecting element through which it passes. The fixing screws 71 and 81 are nevertheless short enough so that their ends do not touch each other.

[0071] The ends of each fixing screw 71 and 81 are threaded and each cooperates with a nut 90. The energy storage device 2 comprises a set of nuts 90, each nut 90 cooperating with both a fixing screw 71 and a fixing screw 81 to fix the second tank 4 to the first tank 3. The first tank 3 is thus fixed to the second tank 4 by means of the fixing screws 71, 81 and the nuts 90. The nuts 90 are held captive by the two walls of the tanks 3 and 4 bearing against each other. Each nut comprises a single tapping receiving on one side the threaded end of a fixing screw 71, and on the other side the threaded end of a fixing screw 81.

[0072] Advantageously, the connecting elements of the first reservoir and the second reservoir comprise flares 91 at their two ends, that is to say that the opening 56 formed in the connecting element is wider at its inlet or its outlet. Each flare forms a depression of generally conical shape from an external face of the reservoir. The juxtaposition of a flare 91 of a connecting element 52 of the first reservoir with a flare of a connecting element 62 of the second reservoir forms a volume in which a nut 90 can be housed. Thus, thanks to the flares 91, the presence of the nuts 90 does not prevent the two reservoirs 3 and 4 from bearing directly on each other.

[0073] [Fig.7] illustrates in more detail a nut 90 cooperating with a fixing screw 71 and with a fixing screw 81. Advantageously, the nut comprises a shape matching the shape of the flares 91 provided at the ends of the connecting elements 52 and 62. The nut 90 includes a first half that engages a connecting member 52 of the first reservoir, and a second half that engages a connecting member 52 of the second tank. The nut 90 has a double tulip shape. The nut generally has a shape of revolution around an axis parallel to the transverse axis Y. This shape includes a larger diameter in its middle, at the interface between the first half and the second half of the nut. The advantage of using a nut whose shape matches the flared shape of the connecting elements is to better distribute any forces exerted by the nut against the walls of a tank. In addition, this makes it possible to provide a nut that is as massive as possible given the volume available for its housing.

[0074] According to the embodiment presented, the first tank is fixed to the second tank by four fixing means as described previously, that is to say by four first fixing screws cooperating respectively with four second fixing screws 81 and four nuts 90. Alternatively, this number could be different, for example one, two, three, five, six or even more fixing means. Not all the connecting elements 52, 62 are necessarily used to fix the tanks 3 and 4 to each other.

[0075] To prevent a screw head 72, 82 from bearing on a flare 91, a plate, for example a washer, is preferably interposed between the screw head and the outer face of a tank. Thus the screw head benefits from a large bearing surface and does not risk damaging the tank.

[0076] Advantageously, the fixing screws 71, 81 serve not only to fix the two tanks 3 and 4 to each other, but they also make it possible to fix various members or accessories to the energy storage device 2. In particular, the plate 14 and / or the spar 5G can be fixed to the first tank 3 by means of fixing screws 71. Similarly, a plate similar to the plate 14 and / or the spar 5D can be fixed to the second tank 4 by means of fixing screws 81.

[0077] Other methods of fixing the first tank to the second tank using connecting elements 52 and 62 could be envisaged. For example, a fixing means could be formed by a single fixing screw passing through a connecting element 52 and a connecting element 62. This single fixing screw could then comprise a screw head bearing against a side wall of a tank and a body cooperating with a nut at the other end of the fixing screw, the nut bearing against a side wall of the other tank. According to yet another embodiment, a single fixing screw could pass through a connecting element of one of the two tanks and cooperate with a threaded insert anchored in the composite structure of the other tank, for example a threaded insert formed in the internal face 55 of a connecting element, in particular a threaded insert of a fixing interface 57 as described previously.These different attachment modes can be combined in the same energy storage device 2 .

[0078] Finally, thanks to the invention, an energy storage device 2 is provided comprising two tanks 3, 4 fixed to each other. Each of the two tanks is easy to manufacture due to its small dimensions. The fixing means used to fix the two tanks together do not take up space around the tanks and therefore do not penalize the overall size of the energy storage device. The energy storage device forms a rigid assembly which can be used as a structural element for the vehicle 1.

Claims

Claims

1. Energy storage device (2) for a motor vehicle (1), comprising a first tank (3) intended to store an energy fluid and a second tank (4) intended to store said energy fluid, the second tank being fixed to the first tank.

2. Energy storage device (2) according to the preceding claim, characterized in that the first reservoir (3) comprises a wall (1 IB) bearing directly against a wall of the second reservoir (4), in particular in that the first reservoir comprises a flat wall (1 IB) bearing directly against a flat wall of the second reservoir.

3. Energy storage device (2) according to one of the preceding claims, characterized in that the first reservoir (3) and the second reservoir (4) each comprise a rigid structure made of a composite material.

4. Energy storage device (2) according to one of the preceding claims, characterized in that the second reservoir (4) comprises a shape symmetrical to the shape of the first reservoir (3).

5. Energy storage device (2) according to one of the preceding claims, characterized in that the first reservoir (3) comprises at least a first pair of opposite walls (1 IA, 1 IB) connected to each other by a first set of connecting elements (52), passing through the first reservoir and extending parallel to a first axis (Y), and in that the second reservoir (4) comprises at least a first pair of opposite walls connected to each other by a first set of connecting elements (62), passing through the second reservoir and extending parallel to the first axis (Y).

6. Energy storage device (2) according to the preceding claim, characterized in that the connecting elements (52) of the first reservoir (3) and the connecting elements (62) of the second reservoir (4) are hollow, each connecting element of the second reservoir extending opposite a connecting element of the first reservoir, the second reservoir being fixed to the first reservoir by a set of fixing means, in particular a set of fixing screws (71, 81), each fixing means passing through a connecting element (52) of the first reservoir and / or a connecting element (62) of the second reservoir.

7. Energy storage device (2) according to the preceding claim, characterized in that the set of fixing means comprises a first set of fixing screws (71) and a second set of fixing screws (81), each fixing screw of the first set of fixing screws passing through a connecting element (52) of the first tank (3), each fixing screw of the second set of fixing screws passing through a connecting elements (62) of the second tank (4), and in that the energy storage device comprises a set of nuts (90), each nut cooperating with a fixing screw of the first set of fixing screws and a fixing screw of the second set of fixing screws to fix the second tank to the first tank.

8. Energy storage device (2) according to the preceding claim, characterized in that the connecting elements (52) of the first reservoir crossed by the first set of fixing screws each comprise a flare (91), and / or in that the connecting elements (62) of the second reservoir crossed by the second set of fixing screws each comprise a flare, each nut (90) being housed in a flare of a connecting element of the first reservoir and / or in a flare of a connecting element of the second reservoir.

9. Arrangement for a motor vehicle (1) comprising a left side member (5G), a right side member (5D) and an energy storage device (2) according to one of the preceding claims, the left side member (5G) being fixed to the first energy storage device (3) and the right side member (5D) being fixed to the second energy storage device (4).

10. Vehicle (1), in particular a motor vehicle, characterized in that it comprises an energy storage device (2) according to one of the preceding claims.

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