Energy storage device for a vehicle, comprising a tank and an electrochemical battery

Abstract

The invention relates to an energy storage device (2) for a motor vehicle (1), comprising: - an electrochemical battery (4), the electrochemical battery comprising a set of electrochemical cells (21) and a casing (23) supporting said set of electrochemical cells, and - a tank (3, 3') for storing an energy fluid, the tank being attached to the casing (23) of the electrochemical battery.

Description

[0001] TITLE: Energy storage device for a vehicle comprising a tank and an electrochemical battery

[0002] Technical field of the invention

[0003] The invention relates to an energy storage device for a vehicle comprising a tank intended to store an energy fluid, in particular hydrogen, and an electrochemical battery. The invention also relates to a vehicle, in particular a motor vehicle, comprising such an energy storage device.

[0004] State of the prior art

[0005] In order to make vehicle use less polluting, vehicles equipped with a fuel cell powered by hydrogen are known. 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. The electrochemical battery can therefore be recharged using the fuel cell. In addition, the electrochemical battery can also be configured to be recharged via an electricity distribution network. Such vehicles include two energy storage means formed on the one hand by the hydrogen tank, and on the other hand by the electrochemical battery.

[0006] The pressure of the hydrogen in the tank can be very high, for example around 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 poses a fire risk 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 into the vehicle.

[0007] On the other hand, electrochemical batteries intended to power an electric motor are also dangerous energy reserves. If damaged, they can ignite and / or cause electric shock or electrocution. An electrochemical battery typically comprises a set of electrochemical cells arranged in a casing supporting and protecting the electrochemical cells from the external environment. The casing protects the other components of the vehicle from any risk of contact with electrical conductors of the electrochemical battery and prevents the escape of gases in the event of a malfunction of an electrochemical cell. An electrochemical battery is also a very large and complex device to integrate within the vehicle. The electrochemical battery generally extends to the level of a vehicle floor.

[0008] Thus, vehicles known from the state of the art which include both a reservoir for an energy fluid and an electrochemical battery to power an electric motor present a poor compromise between autonomy, space available for passengers or for storing objects, and size of the vehicle.

[0009] Presentation of the invention

[0010] The aim of the invention is to provide an energy storage device for a vehicle that overcomes the above drawbacks and improves the energy storage devices known from the prior art. More specifically, a first object of the invention is to provide an energy storage device comprising a tank and an electrochemical battery that is compact and offers optimum safety for users of the vehicle.

[0011] Summary of the invention

[0012] The invention relates to an energy storage device for a motor vehicle, comprising:

[0013] - an electrochemical battery, the electrochemical battery comprising a set of electrochemical cells and a casing supporting the set of electrochemical cells, and

[0014] - a tank intended to store an energy fluid, the tank being fixed to the casing of the electrochemical battery.

[0015] The housing may include a frame extending laterally around the electrochemical cells, and the reservoir may be secured to the frame.

[0016] The energy storage device may comprise at least one first fixing lug fixed, in particular screwed, on the one hand to the tank, and fixed, in particular screwed, on the other hand to the casing of the electrochemical battery.

[0017] The energy storage device may comprise at least one second fixing lug fixed, in particular screwed, on the one hand to the tank, and intended to be fixed, in particular intended to be screwed, on the other hand to a chassis of the vehicle.

[0018] The reservoir may be positioned in a longitudinal extension of the battery, in particular at the rear of the electrochemical battery. The reservoir may comprise a face in direct contact with the casing of the electrochemical battery.

[0019] The tank may comprise a rigid structure made of a composite material, and the tank may be secured to the electrochemical battery housing by fastening screws penetrating the tank structure.

[0020] The 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 reservoir and extending parallel to a first axis, the reservoir comprising at least one attachment interface arranged at one end of at least one connecting element, the reservoir being attached to the casing of the electrochemical battery via the at least one attachment interface.

[0021] The invention also relates to a vehicle, in particular a motor vehicle, comprising a chassis and an energy storage device as defined previously, the casing of the electrochemical battery and the tank being fixed to the chassis.

[0022] The invention also relates to a method for designing an energy storage device as defined above, comprising:

[0023] - the identification of an existing vehicle comprising an electrochemical battery provided with a casing and a set of electrochemical cells supported by said casing, the casing being fixed to a chassis of the vehicle by a set of fixing means, then

[0024] - removing part of the electrochemical cells from the electrochemical battery and reducing the volume of the casing of the electrochemical battery, then - designing a tank intended to store an energy fluid, the tank comprising a geometric shape adapted so that the tank occupies the space freed by the reduction in the volume of the casing, and so that the tank is fixed to the chassis of the vehicle by part of said fixing means.

[0025] Presentation of figures

[0026] 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:

[0027] Figure 1 is a schematic side view of a motor vehicle equipped with an energy storage device according to one embodiment of the invention.

[0028] Figure 2 is a perspective view of a first embodiment of a reservoir of the energy storage device.

[0029] Figure 3 is a partial perspective view of the tank according to the first embodiment.

[0030] Figure 4 is a partial and transparent view of the tank according to the first embodiment.

[0031] Figure 5 is a sectional view of a tank attachment interface according to the first embodiment.

[0032] Figure 6 is a perspective view of a second embodiment of a reservoir of the energy storage device.

[0033] Figure 7 is a perspective and bottom view of an energy storage device according to one embodiment of the invention.

[0034] Figure 8 is a perspective and top view of the energy storage device of Figure 7, an electrochemical battery of the energy storage device being shown without an electrochemical cell. Figure 9 is a longitudinal and vertical sectional view of a portion of the energy storage device of Figure 7.

[0035] Detailed description

[0036] Figure 1 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.

[0037] In this document, the X axis designates the longitudinal axis of vehicle 1. When moving forward and in a straight line, vehicle 1 moves from rear to front in a direction parallel to its longitudinal axis. The X axis is oriented from the front to the rear of the vehicle, i.e., 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, with left and right being defined according to the point of view of a driver of vehicle 1. The Z axis designates the axis perpendicular to the X axis and the Y axis. Vehicle 1 is considered to be 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.

[0038] 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 tank 3, 3' and an electrochemical battery 4. 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 31 supporting, among other things, the energy storage device 2, the fuel cell 5 and the electric motor 6.

[0039] Figures 2 and 6 respectively illustrate a first embodiment of the reservoir 3 and a second embodiment of the reservoir 3'. Where possible, the same references are used to describe the same characteristics of the reservoir 3 and the reservoir 3'.

[0040] According to the illustrated embodiments, the tank 3, 3' is intended to store hydrogen or more precisely dihydrogen. According to other variants, the tank 3, 3' could be configured to store other forms of energy gases, for example liquefied petroleum gas or natural gas. The tank 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.

[0041] Generally speaking, the tank 3, 3' is intended to contain an energy fluid, i.e. a fluid forming a reserve of fluid energy, convertible into an electromotive force capable of moving the vehicle. The tank is therefore a component of the vehicle 1 which gives it a certain autonomy. The tank includes in particular an inlet opening for filling the tank with an energy fluid and an outlet opening for delivering and then consuming the energy fluid contained in the tank. The tank 3, 3' is intended to store the energy fluid under pressure, i.e. at a pressure strictly higher than atmospheric pressure. In this case, the tank is intended to store the energy fluid, in particular hydrogen, at a pressure greater than or equal to 700 Bar.Alternatively, the tank 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. The tank thus comprises a rigid structure capable of withstanding the forces exerted by the pressurized fluid it contains, i.e. centrifugal forces acting from inside the tank and which tend to cause it to burst.

[0042] In addition, the tank 3, 3' may have a capacity greater than or equal to 50 liters, preferably greater than or equal to 100 liters, or even greater than or equal to 150 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.

[0043] The structure of the tank 3, 3' 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.

[0044] Advantageously, the 3.3' tank, the high strength of which is necessary to withstand high pressures of the energy fluid it contains and to guarantee the safety of the passengers of the vehicle 1 in the event of an accident, can be used to stiffen the energy storage device 2, and more generally to stiffen the structure of the vehicle. The tank is capable of supporting the weight exerted by other equipment of the vehicle, and also provides a support for fixing this equipment.

[0045] The tank 3, 3' 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's 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 various static or dynamic loads can exert compressive or shear forces on the tank. These forces are therefore oriented in a different direction from the centrifugal forces exerted by the pressurized energy fluid inside the tank.Advantageously, the resistance of the reservoir necessary to resist the pressure exerted by the energy fluid it contains is therefore also used to support loads which are exerted in different directions.

[0046] The tank 3, 3' may comprise a roughly parallelepiped shape. It may thus comprise three pairs of opposing walls. A first pair of opposing walls is composed of a front wall 7A and a rear wall 7B. The walls 7A and 7B extend substantially parallel to the Y and Z axes. A second pair of opposing walls is composed of a left side wall 8A and a right side wall 8B. The walls 8A and 8B extend substantially parallel to the X and Z axes. A third pair of opposing walls is composed of an upper wall 9A and a lower wall 9B. The walls 9A and 9B extend substantially parallel to the X and Y axes. Alternatively, any other shape of the tank could be envisaged. The tank 3, 3' is arranged in the rear part of the vehicle 1, in particular at a rear part of a base of the vehicle.The tank 3, 3' extends 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 tank can thus be intended to support the load exerted by the rear seats and all the objects stored in the trunk of the vehicle.

[0047] The upper wall 9A may comprise recesses 10 intended to receive the seat base of the vehicle, so that the passengers seated on these seats are not installed too high. Between the recesses 10, the upper wall 9A comprises a projecting central rib 11 which makes it possible to increase the volume of the tank without penalizing the comfort of the passengers seated on the seats above the tank.

[0048] Advantageously, the tank 3, 3' also comprises an anti-submarining device 12. Such a device forms a stop preventing the seating of the seats above the tank from sliding forward in the event of an accident. The anti-submarining device 12 is formed by a protrusion extending forward and upward in front of the recesses 10. The anti-submarining device 12 may comprise a profiled shape along the Y axis and / or extend over the entire width of the tank along the Y axis. In addition to improving passenger safety, the integration of the anti-submarining device 12 into the tank makes it possible to increase the volume of the tank and therefore to increase its energy fluid storage capacity.

[0049] The tank 3, 3' may be isolated from the passenger compartment by a simple protective element, for example made of plastic, which covers the tank. No structural element must be integrated between the tank 3, 3' and the vehicle seats above the tank since the latter has sufficient strength to support the weight of the seats and the passengers sitting on these seats.

[0050] The tank 3, 3' may also provide a support for attaching a safety device. The safety device is intended to protect the vehicle's passengers in the event of an accident. In particular, the safety device may comprise a seat belt and / or a device according to ISO 13216-1:1999, more commonly referred to as the "Isofix" system. These safety devices may be attached to the upper wall 9A of the tank.

[0051] Advantageously, the structure of the tank 3, 3' is made of composite material. Such a material is lighter than steel and even than any other metal for equivalent strength. In addition, the manufacturing processes for components made of composite material make it possible to produce structures with a wide variety of geometric shapes. More complex structural shapes than those obtained from metal can thus be envisaged so as 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.

[0052] The composite material may include a draped or preformed structure, and / or braided and resin-impregnated materials. The composite material may be made from reinforcing elements and a matrix. The reinforcing elements may include 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.

[0053] Figures 3 and 4 illustrate in perspective view the structure of the tank 3 according to the first embodiment. The walls 7A and 7B are connected to each other by a first set of connecting elements 51 extending parallel to the X axis. Similarly, the walls 8A and 8B are connected to each other by a second set of connecting elements 52 extending parallel to the Y axis and the walls 9A and 9B are connected to each other by a third set of connecting elements 53 extending parallel to the Z axis.

[0054] According to an alternative embodiment, the reservoir 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 extend

[0055] 51, 52 and 53 are perpendicular to each other so as to optimally stiffen the tank.

[0056] The connecting elements 51, 52, 53 pass through the 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 7A, 7B, 8A, 8B, 9A, 9B. The connecting elements 51,

[0057] 52, 53 are arranged inside the casing of the tank 3 and not on the periphery of this casing. 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 tank. Thus, the tank 3 is not compartmentalized and the energy fluid can circulate easily inside the tank 3.

[0058] 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.

[0059] Figure 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 tank and is therefore intended to be in contact with the energy fluid, while the internal face 55 communicates with the outside of the tank and is therefore intended to be in contact with the ambient air.

[0060] 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 composite material structure.

[0061] The internal face 55 may be provided in a material different from that forming the structure of the tank. 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.

[0062] 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 tank 3 comprises, for each connecting element, an opening 56 passing right through the tank. 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.

[0063] On the other hand, the openings 56 can be used for the passage of electrical wires and / or hydraulic conduits. This can save the space provided outside the tank for the passage of these electrical wires and / or these hydraulic conduits while providing them with a means of holding them in position. The openings 56 can also be used to allow the evacuation of a liquid from the vehicle, or even to create vents intended to cool or heat the passenger compartment. The openings 56 can also be used to fix various pieces of equipment of the vehicle.

[0064] For this purpose, the tank 3 may 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 may comprise an insert intended to cooperate with a fixing screw 58, for example a fixing screw of type M8 or M10. The insert may 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 may for example comprise a length of between 20 mm and 60 mm inclusive. The insert may be threaded or not threaded. The insert thus provides a fixing means extending deep into the volume of the tank. Such a method of fixing is particularly robust and allows the fixing of heavy loads.

[0065] Each fixing interface 57 makes it possible to fix a piece of equipment of the vehicle against a wall of the tank 3. A fixing interface 57 can be arranged at the end of the opening 56 located on the side of the wall against which the equipment is fixed. Alternatively, a fixing interface 57 could also be arranged at the end of the opening 56 located on the opposite side of the wall against which the equipment is fixed. In this case, an axis or a cable connecting the fixing interface 57 to the equipment could extend inside the opening 56 along the latter. Such an arrangement would for example make it possible to provide fixing interfaces at the level of the lower wall 9B to fix equipment against the upper wall 9A, which would facilitate vehicle assembly or maintenance operations.

[0066] 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 equipment in very varied positions.

[0067] The same equipment can even be attached to the tank 3 using two or more attachment interfaces, so as to secure its attachment. The same equipment can also easily be attached to different positions on the tank, without having to be modified. The same tank 3 can also be easily reused for different vehicle models because the multitude of attachment interfaces provides numerous possibilities for attaching equipment.

[0068] The openings 56 that are not intended to fix vehicle equipment may be plugged with a sealing means so as to prevent the accumulation of mud, sand, earth, stones or any other particles. In particular, the unused openings 56 may be plugged with individual plugs or with a film surrounding the entire tank or any other protective device. The unused openings 56 may possibly be used during the life of the vehicle, for example, to fix new equipment or a new accessory.

[0069] 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.

[0070] According to the second embodiment, the tank 3' is devoid of connecting elements as described previously. The resistance of the tank 3' can then be provided by the thickness of its walls, and possibly by the addition of other reinforcing inserts.

[0071] Generally speaking, and as shown in Figures 7 and 8, the reservoir 3, 3' is positioned in the longitudinal extension of the electrochemical battery 4, at the rear of the electrochemical battery 4. The front wall 7A of the reservoir faces a rear wall of the electrochemical battery 4, or even is in direct contact with a rear wall of the electrochemical battery 4. The energy storage device 2 is thus particularly compact.

[0072] The electrochemical battery 4 can be configured to deliver a direct electric current whose voltage is approximately equal to 400V, or possibly 800V. The electrochemical battery 4 can be recharged by an electric current from the fuel cell 5 and / or by a connection to an electricity distribution network. The electric motor 6 can thus be supplied with energy by an electric current from the electrochemical battery 4. The tank 3, 3' associated with the fuel cell 5 can thus act as a range extender for the vehicle, when the electrochemical battery 4 is discharged.

[0073] The electrochemical battery 4 comprises a set of electrochemical cells 21, for example of the lithium-ion type. The electrochemical cells 21 are electrically connected to each other, for example in series and / or in parallel. The electrochemical cells 21 can be grouped into electrochemical modules. Each electrochemical module thus comprises several electrochemical cells 21. The electrochemical battery 4 can comprise, for example, between two and twenty electrochemical modules. The electrochemical modules are preferably distributed on the same level. The electrochemical battery 4 thus has a height along the Z axis which is relatively restricted, which makes it possible to integrate the electrochemical battery 4 into the underbody of the vehicle. The electrochemical modules can be separated from each other by partition walls 22. The electrochemical battery 4 also comprises a cooling device.The cooling device may comprise a cooling plate, which extends under the electrochemical modules to cool them. Finally, the electrochemical battery 4 may also comprise an electronic controller and electrical conductors, in particular for connecting the electrochemical battery 4 to the electric motor 6.

[0074] The electrochemical battery 4 also comprises a casing 23 supporting and holding the electrochemical cells 21. The casing 23 is fixed to the chassis 31 of the vehicle. The chassis 31 is a part of the body of the vehicle, that is to say a rigid structure, preferably made of steel, which supports all of the components of the vehicle, including the fuel cell 5, the electric motor 6, but also a passenger compartment, a body or even a running gear of the vehicle. In particular, the chassis comprises two side members 32 extending parallel to the longitudinal axis X to the right and left of the vehicle. The casing 23 is fixed to the two side members 32.

[0075] More specifically, the housing 23 comprises a frame 24 extending laterally around the electrochemical cells 21. The frame 24 thus forms a belt which surrounds the electrochemical cells 21 at the front, at the rear, and along their right and left sides. The partition walls 22 extend between the right and left sides of the frame 24.

[0076] The casing 23 is fixed to the chassis 31 via the frame 24. For example, fixing screws may pass through holes provided in the side members 32 and in the frame 24 or in fixing lugs fixed to the frame 24. The casing 23 also comprises a bottom plate 25 fixed to the frame 24. The bottom plate 25 supports all of the electrochemical cells 21. The bottom plate 25 extends substantially horizontally under the electrochemical cells 21 and is preferably made of metal, for example aluminum. The cooling plate previously described preferably extends between the bottom plate 25 and the electrochemical cells 21. The bottom plate 25 makes it possible to protect the electrochemical cells from impacts and / or projections oriented from the bottom to the top. It also makes it possible to protect the electrical conductors of the electrochemical battery from any unwanted contact.

[0077] The housing 23 also includes a top plate 26 attached to the frame 24. The top plate 26 extends substantially horizontally above the electrochemical cells 21 and is preferably made of metal, for example aluminum. The top plate 26 protects the electrochemical cells 21 from downwardly directed projections, in particular from runoff water, and also protects the electrical conductors of the electrochemical battery from any unwanted contact.

[0078] Advantageously, the frame 24 is formed by a series of profiled elements 27 fixed one after the other. Each profiled element 27 is rectilinear and extends horizontally. Each profiled element 27 has a constant section along the direction in which it extends. This section preferably has a rectangular shape with a small horizontal side and a large vertical side. The profiled elements are preferably made of aluminum, which offers a very good compromise between lightness and rigidity. The different profiled elements 27 are preferably welded one after the other. Thus the junction between the profiled elements 27 is watertight. The frame 24 roughly comprises a rectangular shape. It is thus possible to distinguish a front profiled element 27f, a rear profiled element 27r, a right profiled element 27d and a left profiled element 27g.

[0079] The lower plate 25 is fixed, for example screwed, against a lower face of the profiled elements 27. Similarly, the upper plate 26 is fixed, for example screwed, against an upper face of the profiled elements 27. The lower plate 25, the upper plate 26, and the profiled elements 27 thus form a sealed envelope around the electrochemical cells 21.

[0080] The casing 23 extends along the transverse axis Y across the width of the vehicle 1, and is therefore exposed to possible lateral impacts against the vehicle. The casing 23 may comprise shock absorbers capable of absorbing the energy of an impact in the event of the vehicle colliding with an obstacle. The shock absorbers may in particular be positioned along the left and right sides of the casing 23. The shock absorbers may extend parallel to the longitudinal axis X. The shock absorbers may be fixed, in particular screwed or welded, to the profiled elements 27g and 27d.

[0081] According to the invention, the tank 3, 3' is fixed to the casing 23 of the electrochemical battery 4. The fixing of the tank 3, 3' is not carried out by means of a structural element such as an element of the vehicle chassis. On the contrary, the tank 3, 3' is fixed directly or indirectly via a fixing means such as a fixing lug to the casing 23. The rigidity of the battery casing is therefore used to provide at least one support point for the tank. Conversely, the rigidity of the tank is used to provide at least one support point for the electrochemical battery. It is thus possible to obtain a particularly compact energy storage device compared to an arrangement where the electrochemical battery and the tank would be fixed independently of each other to the vehicle chassis. The structure of the tank and the casing 23 of the electrochemical battery reinforce each other.

[0082] In particular, the tank 3, 3' is fixed to the frame 24 which forms a particularly solid structure of the casing. More precisely, the tank 3, 3' is fixed to the rear profiled element 27r.

[0083] According to one embodiment, the energy storage device 2 comprises at least one first fixing lug 41 a, 41 b, 41 c fixed, in particular screwed, on the one hand to the reservoir s, 3', and fixed, in particular screwed, on the other hand to the casing 23 of the electrochemical battery 4. The number of first fixing lugs can be any. According to the embodiment presented, the energy storage device comprises three first fixing lugs 41 a, 41 b, 41 c.

[0084] The first fixing lugs 41a, 41b, 41c are preferably made of metal, for example steel or aluminum. The first fixing lugs 41a, 41b, 41c may be manufactured from a folded metal sheet cut into a given shape. The first fixing lugs 41a, 41b, 41c may comprise first fixing holes cooperating with first fixing screws and with the casing 23 of the battery, in particular with the rear profiled element 27r. The first fixing lugs 41a, 41b, 41c may also comprise second fixing holes cooperating with second fixing screws penetrating into the structure of the tank 3' 3'. Advantageously, the second fixing screws cooperate with fixing interfaces 57 as described previously. The second fixing screws may in particular cooperate with threaded inserts integrated into the structure of the tank.Referring to Figures 2, 6 and 8, the first fixing lug 41a comprises the shape of an L. It comprises a horizontal portion fixed on an upper face (or alternatively on a lower face) of the rear profiled element 27r. The first fixing lug 41a comprises a vertical portion fixed on the front wall 7A of the tank.

[0085] Referring to Figures 2, 6 and 7, the first fixing lug 41 b also comprises the shape of an L. It comprises a transverse portion fixed on a rear face of the rear profiled element 27r. The first fixing lug 41 b comprises a longitudinal portion fixed on the side wall 8A of the tank. The first fixing lug 41 c can be designed symmetrically to the first fixing lug 41 b. The first fixing lug 41 c comprises a longitudinal portion fixed on the side wall 8B of the tank.

[0086] Furthermore, the energy storage device 2 also comprises at least one second fixing lug 42a, 42b, 42c fixed, in particular screwed, on the one hand to the reservoir s, 3', and fixed, in particular screwed, on the other hand to the chassis 31. The number of second fixing lugs can be any. According to the embodiment presented, the energy storage device comprises four second fixing lugs 42a, 42b, 42c, of which only three are visible in FIGS. 2, 6 and 7.

[0087] As for the first fixing lugs 41 a, 41 b, 41 c, the second fixing lugs 42a, 42b, 42c are preferably made of metal, for example steel or aluminum. The second fixing lugs 42a, 42b, 42c may be manufactured from a metal sheet folded and cut into a given shape. The second fixing lugs 42a, 42b, 42c may comprise first fixing holes cooperating with first fixing screws and with the chassis 31 of the vehicle. The second fixing lugs 42a, 42b, 42c may also comprise second fixing holes cooperating with second fixing screws penetrating into the structure of the tank 3' 3'. Advantageously, the second fixing screws cooperate with fixing interfaces 57 as described previously. The second fixing screws can in particular cooperate with threaded inserts integrated into the structure of the tank.The second fixing lugs 42a, 42b, 42c may in particular be fixed against the rear wall 7B and / or against the side walls 8A, 8B of the tank. The second fixing lugs 42a, 42b, 42c may also comprise the shape of an L.

[0088] The number of first fixing lugs 41a, 41b, 41c and second fixing lugs 42a, 42b, 42c may be any. According to one embodiment, the first fixing lugs and the second fixing lugs could form a single flange, or collar. This flange could at least partially surround the tank. The flange is therefore configured to fix the tank 3, 3' to the casing 23 on the one hand and to the chassis on the other hand.

[0089] According to one embodiment, illustrated in Figure 2, the at least one first fixing lug 41a, 41b, 41c and the at least one second fixing lug 42a, 42b, 42c are attached to the structure of the tank 3. The at least one first fixing lug and the at least one second fixing lug are then advantageously fixed to the tank 3 using fixing interfaces 57 as described previously. According to this embodiment, the at least one first fixing lug and the at least one second fixing lug therefore extend completely outside the structure of the tank 3.

[0090] According to a second embodiment, illustrated in Figure 6, the at least one first fixing lug 41 a, 41 b, 41 c and the at least one second fixing lug 42a, 42b, 42c are anchored in the composite material forming the rigid structure of the tank 3'. The at least one first fixing lug and the at least one second fixing lug each comprise a part embedded inside the structure of the tank. The at least one first fixing lug and the at least one second fixing lug are thus integrated into the tank during the manufacture of the composite structure of the tank. As a note, the anchoring of the at least one first fixing lug and / or the at least one second fixing lug in the rigid structure of the tank would also be possible with the tank 3 according to the first embodiment.

[0091] To design the energy storage device 2 previously described, the following design method may be adopted. First, an existing vehicle comprising an electrochemical battery is identified, the electrochemical battery comprising a housing and a set of electrochemical cells supported by said housing, the battery being fixed to a chassis of the vehicle by a set of fixing means. The existing motor vehicle may be, for example, a mass-produced vehicle or one intended to be mass-produced. The housing of the existing energy storage device comprises, in particular, a frame, a bottom plate and a top plate. Next, a portion of the electrochemical cells of said set of electrochemical cells is removed and the size of the battery housing is reduced accordingly. The housing may be truncated so as to extend only around the remaining electrochemical cells.The shapes of the frame, the bottom plate and the top plate can be adapted accordingly so as to form a sealed envelope around the remaining electrochemical cells. This results in a new electrochemical battery with smaller dimensions than the initial electrochemical battery. Reducing the volume of the electrochemical battery frees up space near it. Next, a reservoir is designed for storing an energy fluid whose geometric shape is adapted to occupy the space freed by the reduction in volume of the electrochemical battery. The reservoir may optionally occupy a volume larger than the volume occupied by the part of the initial electrochemical battery that was removed.Advantageously, the tank thus designed is fixed on the one hand to the new electrochemical battery and on the other hand to the chassis using the fixing means provided for fixing the initial electrochemical battery. The energy storage device 2 can therefore be designed and manufactured without modifying or by limiting the modifications made to a chassis initially intended to support only an electrochemical battery 4. This design method can be implemented virtually on a computer, for example by means of computer-aided design (CAD) software.

[0092] Finally, thanks to the invention, we benefit from a vehicle equipped with an energy storage device comprising an electrochemical battery and a reservoir for an energy fluid. The energy storage device is particularly compact and thus allows a large volume to be retained for passengers and / or for transporting objects in the vehicle. The energy storage device is simple to install since it can be housed in place of a pre-existing electrochemical battery. The electrochemical battery and the reservoir can also be easily dismantled, for example for maintenance operations.

Claims

CLAIMS 1. Energy storage device (2) for a motor vehicle (1), comprising: - an electrochemical battery (4), the electrochemical battery comprising a set of electrochemical cells (21) and a casing (23) supporting the set of electrochemical cells, and - a reservoir (3, 3') intended to store an energy fluid, the reservoir being fixed to the casing (23) of the electrochemical battery.

2. Energy storage device (2) according to the preceding claim, characterized in that the casing (23) comprises a frame (24) extending laterally around the electrochemical cells, and in that the reservoir (3, 3') is fixed to the frame.

3. Energy storage device (2) according to one of the preceding claims, characterized in that it comprises at least one first fixing lug (1) fixed, in particular screwed, on the one hand to the reservoir (3, 3'), and fixed, in particular screwed, on the other hand to the casing (23) of the electrochemical battery (4).

4. Energy storage device (2) according to one of the preceding claims, characterized in that it comprises at least one second fixing lug fixed, in particular screwed, on the one hand to the tank (3, 3'), and intended to be fixed, in particular intended to be screwed, on the other hand to a chassis of the vehicle.

5. Energy storage device (2) according to one of the preceding claims, characterized in that the reservoir is positioned in a longitudinal extension of the battery, in particular at the rear of the electrochemical battery (4).

6. Energy storage device (2) according to one of the preceding claims, characterized in that the reservoir (3, 3') comprises a face in direct contact against the casing (23) of the electrochemical battery (4).

7. Energy storage device (2) according to one of the preceding claims, characterized in that the reservoir (3, 3') comprises a rigid structure made of a composite material, and in that the reservoir is fixed to the casing (23) of the electrochemical battery (4) by fixing screws penetrating into the structure of the reservoir.

8. Energy storage device (2) according to one of the preceding claims, characterized in that the reservoir (3, 3') comprises at least a first pair of opposite walls (7A, 7B) connected to each other by a first set of connecting elements (51), passing through the reservoir and extending parallel to a first axis (X), the reservoir comprising at least one fixing interface (57) arranged at one end of at least one connecting element (51, 52, 53), the reservoir being fixed to the casing (23) of the electrochemical battery (4) via the at least one fixing interface.

9. Vehicle (1), in particular a motor vehicle, characterized in that it comprises a chassis (31) and an energy storage device (2) according to one of the preceding claims, the casing (23) of the electrochemical battery (4) and the tank (3, 3') being fixed to the chassis.

10. Method for designing an energy storage device (2) according to one of claims 1 to 8, comprising: - identifying an existing vehicle comprising an electrochemical battery (4) provided with a casing and a set of electrochemical cells supported by said casing, the casing being fixed to a chassis of the vehicle by a set of fixing means, then - removing a portion of the electrochemical cells from the electrochemical battery and reducing the volume of the casing of the electrochemical battery, then - the design of a tank intended to store an energy fluid, the tank comprising a geometric shape adapted so that the tank occupies the space freed up by the reduction in the volume of the casing, and so that the tank is fixed to the chassis of the vehicle by a part of said fixing means.

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