FR2951029A1 - Electric energy storage module e.g. lithium-ion battery module, for electric/hybrid vehicle, has case including upper surface or lower surface supporting face of storage element and forming recess with respect to thickness of case - Google Patents

Abstract

The module has a case (12) defining volume to contain flat electric energy storage elements (8) e.g. electric accumulators. The case forms flat volume with a longitudinal axis and has thickness less than width and length of the case. The case comprises an upper surface (20) or a lower surface (22) supporting a face of one of the storage elements and forming a recess with respect to the thickness of the case. The case is sized for receiving the storage elements placed in a single row along the longitudinal axis of the case on two superimposed levels. Independent claims are also included for the following: (1) a method for positioning an electric energy storage unit on a flat bottom part of a baggage compartment of a vehicle (2) an electric energy storage unit comprising electric energy storage modules.

Description

The invention relates to an electrical energy storage module for a vehicle, more particularly to an electrical energy storage module. the dry battery type and the flat type, as well as an electrical energy storage unit comprising a plurality of modules. The invention also relates to the placement of the module or modules in the vehicle, more particularly in the luggage compartment. The electrical energy requirements of current vehicles, particularly hybrid vehicles, are such that conventional lead-acid batteries no longer meet current constraints, particularly for small vehicles. Flat dry batteries, in particular of the Lithium ion type, are more and more used, in particular for hybrid vehicles. EP 1 833 107 A1 discloses a generally flat and rectangular shaped battery model consisting essentially of a stack of electrode pairs, each pair of electrodes comprising an electrolyte layer between the electrodes. The battery described in this document has the particularity of comprising a layer of insulating material located laterally of the pairs of electrodes. This layer is in contact with collectors arranged sandwiched between two pairs of electrodes and protruding from the electrodes. The insulating layer has bores filled with semiconductor-type material thereby forming a short-circuit resistance of a pair of electrodes. This short-circuit resistance generates a predefined discharge current of the electrode pairs in order to reduce the voltage variations during the different battery function conditions. This document also discloses an electrical energy storage module comprising a series of battery elements as described above, arranged next to each other in juxtaposition of their long sides to be subsequently connected in series. The housing of the module appears to be parallelepipedic in view of the figures and the document does not further specify the shape and construction of the module housing.

US 7,150,938 B2 discloses an electrical power source unit for spacecraft and other vehicles, this unit being generally flat and thin and comprising solar collectors and a series of battery cells arranged flat at the rear of the solar collectors . The batteries are flat and thin and are placed in pockets on the back of the solar collectors to maintain the batteries at a certain temperature level. The battery attachment is then secured by a flexible back panel attached to the solar collectors by means of adhesives. The unit of electrical energy source disclosed by this document is generally large area due to the presence of solar collectors. This type of unit is therefore not suitable for motor vehicles. In addition, it has no flexibility as to its size and therefore to its location in any vehicle.

The document EP 1 577 973 A1 discloses an electrical energy storage unit for motor vehicles, in particular for electric vehicles. The unit comprises a parallelepipedal housing enclosing four rows of six dry battery cells, these elements being flat and rectangular. The unit is intended to be housed in particular in the luggage compartment of the vehicle without the document further specifies the location of the unit in the vehicle. In addition, the document does not further specify the housing enclosing the battery cells. Regardless of the type of battery element used, it appears that none of the documents cited deals in detail with the question of the placement of electrical energy storage units or modules in vehicles and the question of congestion. results from an increased need for storage capacity of electrical energy. The objective of the present invention is to propose a solution to the aforementioned difficulties. The invention consists of an electrical energy storage module, the module comprising a housing defining a volume for containing at least two generally flat electrical energy storage elements, the housing forming a generally planar volume with a longitudinal axis and whose thickness is less than the width and the length; wherein the housing is such that it has at least one upper or lower support wall of a face of a storage member forming a recess relative to the thickness of the housing.

This construction is particularly interesting because it provides a reinforcement of the structure of the housing while ensuring intimate contact between the electrical energy storage elements and the walls of the housing. This intimate contact is interesting from a thermal exchange point of view and the profile of the recessed wall creates a channel capable of cooling the storage elements. According to an advantageous embodiment of the invention, the housing comprises an upper support wall and a lower support wall of opposite faces of one or more storage elements, said walls being in facing relation and forming, each, a recess relative to the thickness of the housing. The provision of this measurement on each main face of the housing is particularly interesting insofar as it allows a more efficient cooling and more homogeneous elements. According to another advantageous embodiment of the invention, the housing is sized to receive the storage elements arranged in a single row along its longitudinal axis, preferably on two superimposed levels. This arrangement is particularly interesting because it allows increased modularity while ensuring satisfactory operation and cooling of the storage elements. Providing two levels of superimposed elements saves space while ensuring cooling from the two outer faces of the elements. Providing only one row optimizes modularity.

According to another advantageous embodiment of the invention, the recess formed by the or one of the support walls extends along the longitudinal axis of the module so as to form, with a wall against, a cooling channel and / or exhaust gas produced by the storage elements, the against wall preferably being part of the module. Ideally, the trunk floor or a sheet or protective plate is used as a counter-wall for the sake of simplicity of construction and cost reduction. According to another advantageous embodiment of the invention, the module comprises means capable of circulating air in the cooling and / or evacuation channel, said means being preferentially of the fan type.

According to another advantageous embodiment of the invention, the housing comprises at least one lateral wall, preferably remote from the storage elements intended to be contained in the housing, said lateral wall forming the thickness of the housing and forming a reinforcement of the housing preferably by compared to efforts essentially in the plane of the side wall. The fact that the side wall is remote from the storage elements makes it possible to create an additional channel that is useful for additional cooling and especially for evacuation of possible fumes or combustion gases in the event of overheating of one or more elements. According to another advantageous embodiment of the invention, the housing is dimensioned so that the wall (s) of support contact (s) a major part, preferably at least 80%, of the corresponding surface of the element or elements (s) storage. This measure is in line with an optimization of the heat exchange capacity. The invention also consists in a method of setting up an electrical energy storage unit on a vehicle floor, in particular on a generally flat bottom of the luggage compartment of the vehicle, comprising the following steps: - setting up on the bottom of the luggage compartment of several modules as described above, the modules being equipped with energy storage elements, the modules being arranged next to each other along a longitudinal or transverse axis of the vehicle; - Laying a protection plate on the modules, the protective plate as a raised bottom of the luggage compartment and supported on the areas of the modules of greater thickness; the protection plate preferably having a stiffening relief, preferably corrugations or embossing.

According to an advantageous embodiment of the invention, the plate is raised to the right of the upper support walls of the modules and resting on the lateral edges of the modules. Raising the plate at this point creates a boss that can be supported on the adjacent portions of the modules that are reinforcement zones. The forces exerted on the protection plate are thus transmitted essentially to these reinforced areas.

According to another advantageous embodiment of the invention, the recess of the lower or upper support wall of a module extends along the longitudinal axis of said module so as to form with the bottom of the trunk or the plate, respectively , a channel for cooling and / or evacuation of gas produced by the storage elements. According to another advantageous embodiment of the invention, the cooling or exhaust duct is connected to an air supply coming from the heating and / or air conditioning system of the vehicle and / or an air supply coming from the vehicle. outside the vehicle.

According to an advantageous embodiment of the invention, the cooling and / or evacuation channel is connected, close to its outlet, to evacuation means capable of guiding the gases coming from the channel towards the outside of the vehicle in case temperature detection device at one or more storage elements exceeding a predefined level, the evacuation means preferably comprising a hatch disposed at a bodywork element of the vehicle in contact with the outside and able to be actuated according to a temperature signal of one or more storage elements. The invention also consists of an energy storage unit intended to be arranged in a vehicle luggage compartment, the box being equipped with a generally flat bottom, characterized in that it comprises several modules as described below. front intended to be arranged next to each other on said bottom of the luggage compartment, and a protection plate having a stiffening relief, preferably corrugations or embossing, intended to be disposed on said modules.

According to an advantageous embodiment of the invention, the protection plate has a raised profile to the right of the upper support faces of the modules and matching the adjacent side edges of the modules. The forces exerted by luggage on the protection plate are thus transmitted mainly to these reinforced areas, thus preserving the storage elements.

According to an advantageous embodiment of the invention, the recess of the lower or upper support wall of a module extends along the longitudinal axis of said module so as to form with the bottom of the box or the plate, respectively, a channel for cooling and / or evacuation of gas produced by the storage elements. Other features and advantages of the present invention will be better understood with the aid of the description and the drawings, in which: FIG. 1 is a perspective view of a bodywork element constituting the bottom plate of the luggage compartment; a vehicle, the sheet including a housing for the spare wheel. Figure 2 is a perspective view of the bodywork element of the figure with a trim panel comprising an access door to the housing of the spare wheel. Figure 3 is a perspective view corresponding to Figure 2 where four sets of four battery elements are arranged on the trim panel. Fig. 4 is a perspective view of an electric energy storage unit portion disposed on a luggage compartment bottom and covered with a guard plate. Fig. 5 is a perspective view of an arrangement of four battery cells forming a module. Figure 6 is a perspective view of an alternative arrangement of four battery cells forming a module. A bottom plate 2 luggage compartment is illustrated in Figure 1. This is the sheet forming part of the bottom of the trunk and forming the housing for the spare wheel. The sheet in question has a series of reinforcing bosses and passages or housings of various accessories. Although other bodywork elements are added to this sheet to complete the bottom of the luggage compartment, it remains the main body component having the largest area of the trunk floor. FIG. 2 illustrates the trunk floor sheet 2 of FIG. 1, where the upper surface of the sheet in question is covered with a covering panel 4. This panel covers the recess formed by the spare wheel housing and forms thus a bottom floor of chest. A hatch 6 to access the housing of the spare wheel is provided in the panel 4. Such an access hatch 6 is typically pivotally mounted relative to the edge opposite the handle or latch, this edge being the front edge according to the direction of vehicle advancement (when the luggage compartment is located at the rear of the vehicle). The pivoting mounting of the hatch can be provided by hinges or by a fitting to remove the hatch 6 of the trim panel 4. Figure 3 illustrates the trunk bottom sheet covered with a trim panel according to Figure 2, with a series of electrical energy storage elements 8 disposed on the trim panel. These storage elements are of flat shape and electric accumulator type that is to say able to convert the electrical energy into another form (chemical and / or electrostatic) to store it and able to restore it later.

Electrical energy can indeed be stored in particular in the form of electrostatic energy, by accumulating electrical charges in one or more capacitors. The appearance of capacitors whose capacity can reach a few hundred farads makes it possible to substitute conventional storage batteries. The advantages are a decrease in weight and possible operation in very cold weather. The major disadvantage is the much higher stored Wh price. The electrical energy can also be stored in electrochemical form which has the interesting characteristic of providing a voltage (potential difference) across the battery that is not dependent on its load (amount of energy stored) or the current output. Chemical electric accumulators use the property of certain chemical couples to accumulate a certain quantity of electricity by modifying their molecular structure in a reversible manner. There are various embodiments of this type of electric accumulator, such as Ni-Cd (nickel-cadmium), Ni-MH (nickel-metal hydride), Ni-Zn (nickel-zinc) and lithium. Among Lithium batteries, there is Lithium metal technology where the negative electrode is made of lithium metal (material that poses safety problems), and lithium ion technology, where the lithium remains in the ionic state thanks to the use of an insertion compound both at the negative electrode (generally in graphite) and at the positive electrode (cobalt dioxide, manganese, iron phosphate). Unlike other technologies, Li-ion batteries are not linked to an electrochemical couple. Any material that can accommodate lithium ions can be the basis of a Li-ion battery. The lithium-ion battery operates on the reversible exchange of lithium ion between a positive electrode, most commonly a lithiated transition metal oxide (cobalt dioxide or manganese) and a graphite negative electrode. The voltage of a Li-Ion element is 3.6 V.

This technology offers the highest specific energy (energy / mass) and the highest energy density (energy / volume), which is why it is preferred in electric or hybrid vehicle applications. This misused technology presents potential dangers: batteries can degrade by heating above 80 ° C in a brutal and dangerous reaction. Lithium-ion batteries should always be handled with extreme care by avoiding piercing the casing, as short-circuiting of these batteries can lead to an explosion. This safety problem requires the integration of an electronic protection system preventing too deep a charge or discharge, to provide protection of the battery boxes and a cooling device of sufficient capacity. By their current construction by superposition of flat electrodes, these batteries are generally generally flat or generally parallelepipedic shape. The arrangement provided in FIG. 3 consists in arranging several modules 10 of four elements 8 next to one another, in this case four modules 10 arranged next to each other parallel to the longitudinal axis of the vehicle. Each module comprises four elements 8, that is to say two elements arranged in the same plane and aligned along their longitudinal axes, each of these two elements being covered with a superimposed element so as to form an alignment of two pairs of elements. superimposed elements. Figure 3 is limited to illustrate the arrangement of the batteries knowing that they are arranged in a module in housings as illustrated in Figure 4 and described below. It should be noted that the arrangement of the figure is purely illustrative and not limiting. Indeed, it is quite possible, even desirable, to provide an alignment of more than two elements along the longitudinal axis of the vehicle, depending on the space available in the vehicle. It is also conceivable to arrange the modules transversely to the longitudinal axis of the vehicle or to provide a superposition of the elements on three or more levels or to provide no superposition, that is to say a single "layer" of elements. FIG. 4 illustrates part of an electrical energy storage unit comprising a plurality of modules each comprising a housing 12 housing four battery cells, the modules being arranged next to one another and being covered with a protective plate 11 serving as a raised chest floor. A housing 12 whose geometry will be detailed below contains several battery elements, more particularly four elements of generally parallelepipedic shape whose main axis of each is parallel to the longitudinal axis of the housing and included in a vertical transverse plane comprising this axis. The four elements 8 are schematically illustrated by rectangular parallelepipeds for simplification of illustration and presentation. The contact terminals of the elements which will be detailed in relation to FIGS. 5 and 6 are not shown. The housing 12 has a very particular geometry enabling it to ensure, in combination with the protective plate 11, a dual function in addition to keeping the elements together, namely to protect the elements relative to objects deposited in the trunk and to ensure cooling of the elements. The housing has a rectangular parallelepiped general shape of greater width than the elements, typically of the order of a few percent, ideally of the order of 5% to 20%. The housing however comprises a recess of the upper face 20 and the lower face 22. These upper 20 and lower 22 faces are in direct contact with the outer major surfaces of the elements 8. This geometry allows the formation of a reinforcement on each side lateral, parallel to the longitudinal axis of the housing. This reinforcement is formed by the lateral face 24 of the housing and the upper and lower face portions directly adjacent to the lateral face ensuring the reduction of thickness of the housing from the side face to the recess. These parts of upper and lower faces have indeed a rounded profile with two curvatures of opposite concavities. It should be noted that this profile can take different forms, such as a form of angular advantage. It is also conceivable to provide ribs in the volume formed by this zone. These reinforcements on each side of the housing makes it particularly rigid in a vertical transverse plane.

The housing can be made of different materials depending on various sizing and manufacturing parameters. Ideally it is made of plastic material preferentially extruded. The electrical storage elements are then connected together and slid into the housing from an opening at one end. The housing could also be made of sheet metal. In this case, special care must be taken in the area of electrical insulation with respect to the terminals of the elements. The housing would in this case ideally consist of several stamped sheet metal elements and then assembled to form the closed housing at its periphery about its longitudinal axis. Other variants of the manufacturing process and the choice of materials are possible.

A protective plate or plate 11 is disposed on the housings 12 disposed adjacent to one another adjacent to each other along their lateral edges parallel to the longitudinal axis. The protective plate 11 has a profile with longitudinal bosses conforming to the upper face portions of the housings forming the reinforcing zones at the lateral edges. In addition, the sheet has a raised profile between two bosses so as to be remote from the upper face 16 of the housing at the recess. This arrangement provides a remarkable mechanical protection of the electric accumulator elements insofar as the generally vertical mechanical forces exerted by objects disposed in the trunk are taken up by the bosses and the reinforcement areas of the housings, thus preserving the elements. It should be noted that this particular form of the sheet or protective plate 11 is not mandatory. Indeed, an essentially flat plate or protection plate would also ensure the transmission of vertical forces from the objects placed in the trunk to the reinforcement areas of the housings. The profiled shape of the sheet or protective plate as illustrated in FIG. 4, however, provides stiffening from a bending point of view of the zone situated above the upper face of the casing and thus optimizes the recovery of the stresses. concentrating them towards the reinforcement zones, in the manner of a vault.

The upper and lower recess areas of the housing 12 together with the protective plate 11 and with the upper surface 14 of the bottom of the box, respectively, two longitudinal channels 16 and 18. These channels, by their longitudinal arrangement and the fact that they are delimited by the faces of the housing which are in direct contact with the elements 8, makes them particularly interesting for the purpose of cooling the elements in question. These channels are also useful for the evacuation of possible fumes such as those that can be produced during the overheating of one or more elements. The reinforcement zones at the two lateral edges of the housing also constitute, each, a channel 21 particularly adapted to the evacuation of fumes to the extent that it is in direct contact with the elements. This channel 21 can also serve as a cooling channel but to a lesser extent given the smaller exchange surface with the elements. Such additional cooling ensures a more uniform temperature of the elements.

The design of the modules as illustrated in FIG. 4 combined with the protective plate ensures, in addition to the maintenance of the electric accumulator elements, the dual function of mechanical protection of the elements with respect to the objects arranged in the trunk and cooling and / or evacuation of combustion gases from the elements. The means used are particularly simple and compact. The extra thickness imposed by the cooling channels is optimized insofar as the walls delimiting these channels comprise elements that are otherwise present, such as the upper surface of the bottom of the box and the protective plate. Means for circulating air along the channels are necessary. The channels or at least some of them can be connected directly with an air intake of the heating and / or air conditioning system of the vehicle. Such an arrangement is particularly interesting because it avoids the disadvantages associated with the presence of one or more fans dedicated to this air flow (extra cost, space, noise, ...). Alternatively, one can of course provide such fans, especially when the construction of the vehicle is such that no air supply is available near the power storage modules. It is also possible to envisage one or more fans dedicated for this purpose when the need for air flow is particularly important, for example, when the channel (s) are particularly narrow or of small section or when the operating conditions of the elements require a increased cooling.

The output of the channels can simply open freely in the rear part of the volume of the trunk, so that the air heated through its passage in these channels is evacuated by the exit valves of the passenger compartment of the vehicle. These valves are typically arranged towards the rear of the vehicle, near the volume of the trunk. In case of detection of failure of one or more elements, for example on the basis of a temperature detection, it is conceivable to activate a device for deflecting the output of certain channels directly to the outside of the vehicle. The outer walls to the housings, delimiting the upper channels 16 and lower 18, that is to say the protective plate 11 and the upper surface 14 of the trunk floor, can be integrated into the housings. Indeed, it is conceivable to provide the housings with a double upper and / or lower wall, so as to directly form one or more channels. The electrical accumulator elements of a module are typically connected in series. To do this, several arrangements of the elements are possible. Figure 5 illustrates a first arrangement where the four elements are oriented so that their terminals are all directed in the same direction. In this case, a first connector 26 connecting the positive terminal of the low front element 82 with the negative terminal of the high front element 81. A second connector 28 connects the positive terminal of the high front element 81 with the negative terminal. of the rear high element 83. A third connector 30 connects the positive terminal of this rear high element 83 to the negative terminal of the low rear element 84. The module is thus connected to the vehicle's electrical system via the negative terminal of the vehicle. front lower member 82 and via a fourth connector 32 to the positive terminal of the low back element 84. Figure 6 illustrates another arrangement of the elements in a module. The elements are oriented so that their terminals are vis-à-vis. The positive terminal of the front high element 81 is connected via a first connector to the negative terminal of the high rear element 83. The positive terminal of this rear high element 83 is connected via a second connector 36 to the negative terminal of the rear lower element 84. The positive terminal of this low rear element 84 is connected via a third connector 38 to the negative terminal of the low front element 82. The module is thus connected to the electrical system of the vehicle via connectors to the terminal negative of the front high element 81 and the positive terminal of the front low element 82.

These two arrangements are those which minimize the length of the connectors but other arrangements are possible. Whatever the arrangement considered, it will be necessary to provide an electrical insulation of the terminals, in particular in the case of the arrangement of Figure 6. Once the elements arranged and connected together as shown in Figure 5 or 6, these can be inserted into the housing to form a module ready to be disposed with others to form an electrical energy storage unit.

Claims (15)

Revendications1. An electrical energy storage module, the module comprising a housing (12) defining a volume for containing at least two generally flat electrical energy storage elements (8), the housing (12) forming a generally planar volume with a longitudinal axis and whose thickness is less than width and length; characterized in that the housing (12) is such that it has at least one upper (20) or lower (22) support wall of one side of a storage element (8), forming a recess relative to the thickness of the case. 2. An electrical energy storage module according to the preceding claim, characterized in that the housing (12) comprises an upper support wall (20) and a lower support wall (22) of opposite faces of one or more elements. storage, said walls (20, 22) being vis-à-vis and each forming a recess relative to the thickness of the housing. Electrical energy storage module according to one of the preceding claims, characterized in that the housing (12) is dimensioned to receive the storage elements (8) arranged in a single row along its longitudinal axis, preferably on two superimposed levels. 4. An electrical energy storage module according to one of the preceding claims, characterized in that the recess formed by the or one of the support walls extends along the longitudinal axis of the module so as to form, with a counter wall (11, 14), a channel (16, 18) for cooling and / or evacuation of gas produced by the storage elements, the against wall preferably being part of the module. 5. Storage module of electrical energy according to the preceding claim, characterized in that it comprises means adapted to circulate air in the cooling channel and / or discharge, said means being preferably of the fan type . 14 Electrical energy storage module according to one of the preceding claims, characterized in that the housing (12) comprises at least one side wall (24), preferably at a distance from the storage elements (8) intended to be contained in the housing (12), said lateral wall forming the thickness of the housing and forming a reinforcement of the housing preferentially with respect to forces essentially in the plane of the side wall. 7. The electrical energy storage module according to one of the preceding claims, characterized in that the housing (12) is dimensioned so that the wall or walls (s) of support (20, 22) contact (nt ) a major portion, preferably at least 80%, of the corresponding surface of the storage element (s). 8. A method of setting up an electrical energy storage unit on a vehicle floor, in particular on a generally flat bottom of the luggage compartment of the vehicle, comprising the following steps: - setting up on the bottom of the trunk luggage bag of several modules according to one of the preceding claims, the modules being equipped with energy storage elements (8), the modules being arranged next to each other along a longitudinal or transverse axis of the vehicle; - Laying a protection plate (11) on the modules, the protective plate as a raised bottom of the luggage compartment and supported on the areas of the modules of greater thickness; the protection plate preferably having a stiffening relief, preferably corrugations or embossing 9. A method of setting up an electrical energy storage unit in a vehicle according to the preceding claim, characterized in that the protection plate (11) is raised to the right of the upper support walls of the modules and in support on the lateral edges (24) of the modules. 10. A method of setting up an electrical energy storage unit in a vehicle according to one of claims 8 to 9, characterized in that the recess of the lower support wall (22) or upper (20) of a module extends along the longitudinal axis of said module so as to form with the bottom of the box (14) or the protection plate (11), respectively, a cooling channel (18, 16) and / or evacuation of gas produced by the storage elements. 11. A method of setting up an electrical energy storage unit in a vehicle according to the preceding claim, characterized in that the cooling or evacuation channel (16, 18) is connected to an air inlet. from the vehicle's heating and / or air conditioning system and / or an air intake from outside the vehicle. 12. A method of setting up an electrical energy storage unit in a vehicle according to one of claims 10 and 11, characterized in that the cooling and / or evacuation channel (16, 18) is connected, near its outlet, to evacuation means able to guide the gases coming from the channel towards the outside of the vehicle in the event of temperature detection at one or more storage elements exceeding a predefined level, the evacuation means preferably comprising a hatch disposed at a bodywork element of the vehicle in contact with the outside and able to be actuated as a function of a temperature signal of one or more storage elements. 13. Energy storage unit intended to be arranged in a vehicle luggage compartment, the trunk being equipped with a generally flat bottom, characterized in that it comprises several modules according to one of claims 1 to 7 for be placed next to each other on said bottom of the luggage compartment, and a protection plate (11) having a stiffening relief, preferably corrugations or embossing, intended to be disposed on said modules. 14. Storage unit according to the preceding claim, characterized in that the protection plate (11) has a raised profile to the right of the upper support faces of the modules and marrying the adjacent side edges of the modules. 15. Storage unit according to the preceding claim, characterized in that the recess of the lower support wall (22) or upper (20) of a module extends along the longitudinal axis of said module so as to form with the bottom of the trunk or the plate, respectively, a channel for cooling and / or evacuation of gas produced by the storage elements.