Electrical energy storage device with electrical connector cooling system

Abstract

Title of the invention: Electrical energy storage device with electrical connector cooling system The present invention relates to an electrical energy storage device (1) for a vehicle comprising at least a plurality of electrochemical cells (2), at least two adjacent cells (2) comprising an electrical connection portion (10) connecting the two cells (2), the electrical connection portion (10) and the two cells (2) delimiting a housing (40), the electrical energy storage device (1) comprising a cooling system (24) using dielectric fluid, this cooling system (24) comprising a plurality of spray pipes (38) intended to project the dielectric fluid, at least one of said pipes (38) extending into the housing (40). Abstract figure: Figure 1

Description

Title of the invention: Electrical energy storage device with electrical connector cooling system

[0001] The present invention relates to the field of thermal regulation devices and more particularly to the means implemented to regulate the temperature of electrical energy storage devices equipping vehicles.

[0002] It is known nowadays to equip electric, thermal or hybrid vehicles with electrical energy storage devices allowing an electrical supply to the various elements of the vehicle. These electrical energy storage devices are generally composed of electrochemical cells positioned in a battery pack.

[0003] During operation of the vehicle, the battery pack can release a significant amount of heat and therefore be subjected to temperature increases which can cause it to be damaged or even destroyed in certain cases. Consequently, its cooling is essential in order to keep it in good condition and thus ensure the reliability, autonomy and performance of the vehicle. To do this, one or more thermal regulation devices intended to regulate the temperature of the battery pack are implemented to ensure the cooling functions of the electrical or electronic components inside this battery pack, and thus optimize the operation of its various components.

[0004] Such thermal regulation devices are, for example, cooling systems, which are generally traversed by a heat transfer fluid which absorbs the heat emitted by the cells of the battery pack in order to cool it for proper operation.

[0005] Within a battery pack, the electrochemical cells have electrical connection portions, which are electrical connection areas that allow the cells to be connected together. They are commonly referred to by the term "TAB" in English literature, particularly in patents. These electrical connection portions correspond to the hottest points of the cells when they are in operation. Document FR3099643 describes a thermal regulation device aimed at cooling these connections more specifically, but it has, among other drawbacks, that of its size, which seriously affects the energy density of the pack as a whole. The present invention aims to overcome this drawback by proposing a thermal regulation device that specifically targets these electrical connection portions or "TAB" while preserving the compactness of the pack.

[0006] The main subject of the present invention is thus an electrical energy storage device for a vehicle comprising at least a plurality of electrochemical cells, at least two adjacent cells comprising an electrical connection portion connecting the two cells, the electrical connection portion and the two cells delimiting a housing, the electrical energy storage device comprising a dielectric fluid cooling system, this cooling system comprising a plurality of spray pipes intended to project the dielectric fluid, at least one of said pipes extending into the housing.

[0007] The electrical energy storage device according to the invention allows, thanks to its cooling system, cooling as close as possible to the electrical connection portions, which are the hottest points of the device when it is in operation, for example during the charging and discharging cycles of the electrochemical cells. These electrical connection portions connect adjacent cells, that is to say electrochemical cells which are directly side by side within the electrical energy storage device. Between two adjacent cells, the electrical connection portions participate in delimiting housings within which the spraying conduits extend. There is thus one spraying conduit per housing.Such an arrangement of the spray lines, as close as possible to the electrical connection portions and in an otherwise unused volume of the electrical energy storage device, results in the compactness of the cooling system.

[0008] The electrical connection portions are made of metal, for example copper or aluminum. The dielectric fluid which flows through the cooling system may in particular be an oil which is resistant to voltages of more than 2500 V. Such an oil makes it possible to cool the electrical connection portions without electrical risk.

[0009] According to a characteristic of the invention, the cells comprise electrodes, one end of which forms an electrical connector which delimits the housing.

[0010] There is therefore at least one electrical connector per electrochemical cell, formed by one end of an electrode forming part of the electrical connection portion. The electrical connectors correspond to current connectors at the output of the electrochemical cells and may be positive poles or negative poles. They are made of the same material as the internal portions of the electrodes of which they constitute one end.

[0011] According to another characteristic of the invention, the electrical connector has a folded end part which delimits the housing.

[0012] This end part is more particularly folded towards the space existing between the electrical connectors of two adjacent cells.

[0013] According to one characteristic, the folded end portions of an electrical connector of a given cell and of an electrical connector of an adjacent cell are juxtaposed to delimit the housing.

[0014] The end portions of the electrical connectors of two adjacent cells fold against each other or over each other; they are thus folded at substantially right angles, the end portion of a given cell covering that of the adjacent cell.

[0015] According to a characteristic of the invention, the folded end parts comprise at least one welded zone.

[0016] It is understood that this welded zone allows the folded end parts of two adjacent cells to be held in position when they are juxtaposed. The welded zone corresponds, for example, to a welding point between these folded end parts.

[0017] According to one feature, the cooling system comprises at least one supply line and at least one transverse manifold connected to the supply line, the spray lines extending from the transverse manifold.

[0018] The feed pipe extends along a main extension direction of the electrochemical cells, while the transverse feeder is arranged opposite a face of these electrochemical cells which comprises the electrical connection portions. The feed pipe and the transverse feeder are for example substantially perpendicular to each other.

[0019] According to another characteristic of the invention, the spray pipes project perpendicularly relative to an extension dimension of the transverse manifold.

[0020] The dielectric fluid can thus be distributed equally within each of the spray lines, so as to uniformly cool all the electrical connection portions of the electrical energy storage device.

[0021] According to one feature, spray orifices are provided through a wall of the spray pipes.

[0022] These orifices are thus flush with the wall of the spray pipes. The absence of a projecting element, for example in the form of spray nozzles, allows space to be saved. The orifices can be, for example, calibrated holes or calibrated slots.

[0023] According to one characteristic, an end cell comprises a folded plate in contact with an electrical terminal of the electrical energy storage device.

[0024] Such a plate extends away from the cell adjacent to the end cell which carries it, i.e. towards an exterior of the energy storage device. electrical. This plate is in contact with an electrical terminal, which is an area through which the current arrives or leaves and which supplies the plurality of cells. There may be a positive electrical terminal and a negative electrical terminal within the electrical energy storage device, arranged in different configurations depending on the embodiments.

[0025] According to a characteristic of the invention, the electrical energy storage device comprises a housing within which the cells are arranged, the cooling system being arranged along partitions of the housing.

[0026] This housing is a sealed box which constitutes a housing for the electrochemical cells. The cooling system is arranged within the housing, so that its supply pipe and its transverse manifold are arranged between partitions of the housing and the electrochemical cells.

[0027] According to another characteristic of the invention, a bottom wall of the housing comprises a dielectric fluid receiving zone.

[0028] The bottom wall thus allows the collection of the dielectric fluid when it has been sprayed onto the electrical connection portions, with a view to its evacuation from the housing.

[0029] The invention further relates to a motor vehicle comprising at least one electrical energy storage device as mentioned previously.

[0030] The electrical energy storage device is, within this motor vehicle, connected to a pump connected to the cooling system as well as to a reservoir of the dielectric fluid.

[0031] The invention further relates to a method of assembling an electrical energy storage device as mentioned previously, comprising a step of positioning at least one of the spray pipes between the electrical connectors of two adjacent cells, a step of folding the end parts of the electrical connectors so as to delimit the housing, and a step of welding said end parts.

[0032] These steps of the assembly method can be carried out in different chronological orders; there can thus be, successively, the positioning step, then the folding step, then the welding step, or even the folding step, then the welding step, then the positioning step.

[0033] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and examples of embodiment given for informational and non-limiting purposes with reference to the appended drawings on the other hand, in which:

[0034] [Fig-1] illustrates, schematically, a perspective view of a storage device electrical energy according to the invention, a housing of this electrical energy storage device having been lifted;

[0035] [Fig.2] illustrates, schematically, an exploded view of a plurality of electrochemical cells and a cooling system of the electrical energy storage device of [Fig.l];

[0036] [Fig.3] illustrates, schematically, one end of the electrical energy storage device of [Fig.l] according to a sectional view;

[0037] [Fig.4] illustrates, schematically, a close-up view of the cooling system of [Fig.2] and of a housing receiving a spray line of this cooling system;

[0038] [Fig.5] illustrates, schematically, the end of the electrical energy storage device of [Fig.3], a housing being partially closed by folded end parts;

[0039] [Fig.6] illustrates, schematically, the end of the electrical energy storage device of [Fig.3], the housing being completely closed by the folded end parts.

[0040] The features, variants and the different embodiments of the invention may be combined with each other, in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0041] In the figures, the elements common to several figures retain the same reference.

[0042] In the detailed description which follows, the terms “longitudinal”, “transverse” and “vertical” refer to the orientation of the thermal regulation device according to the invention. A longitudinal direction corresponds to a main extension direction of the electrical energy storage device, this longitudinal direction being parallel to a longitudinal axis L of a reference frame L, V, T illustrated in the figures. A transverse direction corresponds to a direction of alignment of the electrochemical cells, this transverse direction being parallel to a transverse axis T of the reference frame L, V, T and this transverse axis T being perpendicular to the longitudinal axis L. Finally, a vertical direction corresponds to a direction parallel to a vertical axis V of the reference frame L, V, T, this vertical axis V being perpendicular to the longitudinal axis L and to the transverse axis T.

[0043] [Fig.l] thus illustrates, schematically, an electrical energy storage device 1 according to the invention. Such an electrical energy storage device 1 is intended to equip a vehicle, for example a motor vehicle, in order to electrically supply its various components.

[0044] The electrical energy storage device 1 comprises a plurality of electrochemical cells 2, which are aligned one after the other in a transverse direction T. The electrochemical cells 2 extend mainly in a longitudinal direction L, and they have a main body 3 which has a substantially rectangular general shape. The electrochemical cells 2 are composed of several sheets superimposed on each other in the transverse direction T, the sheets comprising conductive materials and at least one electrode 4. Each electrochemical cell 2 here comprises two electrodes 4, with a positive electrode 4 and a negative electrode 4. Each of these electrodes 4 comprises an end which extends beyond the main body 3 of the electrochemical cell 4 and projects therefrom.The ends of the electrodes 4 more precisely protrude from a longitudinal end face 6, 8 of the electrochemical cells 2, each electrochemical cell 2 thus having one end of its positive electrode 4 which extends from a first longitudinal end face 6 and one end of its negative electrode 4 which extends from a second longitudinal end face 8, or conversely one end of its positive electrode 4 which extends from the second longitudinal end face 8 and one end of its negative electrode 4 which extends from the first longitudinal end face 6.

[0045] The ends of the electrodes 4 are arranged in electrical connection portions 10 of the electrical energy storage device 1, which make it possible to electrically connect two electrochemical cells 2 to each other. The electrical connection portions 10 are more precisely formed by two adjacent electrochemical cells 2, both at the first longitudinal end face 6 and the second longitudinal end face 8 of the electrochemical cells 2.

[0046] Within the electrical connection portions 10, the ends of the electrodes 4 form electrical connectors 12, which correspond to the parts of the electrochemical cells 2 which ensure their connection to the electrochemical cells 2 which are adjacent to them. There is therefore at least one electrical connector 12 per electrochemical cell 2; more precisely, there is here an electrical connector 12 at the first longitudinal end face 6 of each electrochemical cell 2 and an electrical connector 12 at their second longitudinal end faces 8. These electrical connectors 12 are made of material with a central portion of the electrodes 4 which is arranged within the main body 3 of the electrochemical cells 4. The electrical connectors 12 formed by the negative electrodes 4 can for example be made of copper while the electrical connectors 12 formed by the positive electrodes 4 are made of aluminum.

[0047] The electrical energy storage device 1 comprises a housing 14 which is a sealed box within which the electrochemical cells 2 are arranged, this housing 14 being shown in [Fig.l]. The housing 14 has a substantially rectangular shape, and extends between a first longitudinal end 16 facing the first longitudinal end face 6 of the electrochemical cells 2 and a second longitudinal end 18 facing their second longitudinal end face 8. These first longitudinal ends 16 and second longitudinal ends 18 of the housing 14 are connected, in a vertical direction V, by a bottom wall 20 and by an opposite wall 22.

[0048] In addition to the electrochemical cells 2, the housing 14 contains a dielectric fluid cooling system 24 for the electrical energy storage device 1. Such a cooling system 24 allows cooling of the electrochemical cells 2 during their operation, and more particularly cooling of their electrical connection portions 10, thanks to circulation of the dielectric fluid within the housing 14.

[0049] The dielectric fluid is conveyed into the housing 14 via a fluid inlet nozzle 26 and is discharged therefrom via a fluid outlet nozzle 28, both of which are here arranged at the first longitudinal end 16 of the housing 14. The fluid inlet nozzle 26 is directly connected to the cooling system 24, i.e. it is connected to a pipe of this cooling system 24, while the fluid outlet nozzle 28 opens onto a partition of the housing 14 which constitutes its first longitudinal end 16. The circulation of the dielectric fluid takes place, within the motor vehicle, thanks to a reservoir of dielectric fluid which allows the supply of the cooling system 24, such circulation being further facilitated by the presence of a pump which is connected to this cooling system 24. The circulation of the dielectric fluid is illustrated in FIG. [Fig.3] by arrows.

[0050] The cooling system 24 is for example made of plastic. It comprises a supply pipe 30 which extends within the housing 14, along one of its partitions and in the longitudinal direction L. The supply pipe 30 is further arranged close to the bottom wall 20 rather than the opposite wall 22. The supply pipe 30 is connected, at each of its longitudinal ends, to a transverse feeder 32. It is thus understood that there is a transverse feeder 32 arranged along the partition of the housing 14 which forms its first longitudinal end 16, that is to say in the vicinity of the first longitudinal end faces 6 of the electrochemical cells 2, and another transverse feeder 32 arranged along the partition of the housing 14 which forms its second longitudinal end 18, i.e. in the vicinity of the second longitudinal end faces 8 of these electrochemical cells 2.

[0051] The transverse feeder 32 arranged at the level of the first longitudinal end 16 of the housing 14 will now be described in detail, but the characteristics which follow may be applied mutatis mutandis to the transverse feeder 32 arranged at the level of the second longitudinal end 18 without departing from the scope of the invention.

[0052] The transverse feeder 32 is substantially perpendicular to the supply pipe 30. It extends in the transverse direction T between a first end 34 which opens onto this supply pipe 30 and a second end 36 opposite the first end 34. The transverse feeder 32 is furthermore connected, at this first end 34, to the fluid inlet endpiece 26, while the fluid outlet endpiece 28 is arranged on the housing 14 opposite the second end 36.

[0053] From its first end 34 to its second end 36, the transverse feeder 32 is equipped with a plurality of spraying conduits 38. Such spraying conduits 38 extend mainly in the vertical direction V, perpendicular to the transverse direction T in which the transverse feeder 32 extends from its first end 34 to its second end 36. The spraying conduits 38 are intended to project the dielectric fluid onto the electrochemical cells 2, and more precisely onto their electrical connection portions 10. For this purpose, they are arranged within housings 40 formed within the electrical connection portions 10 between two adjacent electrochemical cells 2, so that each spraying conduit 38 extends into a housing 40.

[0054] The housing 40 is delimited by the electrical connectors 12. With the exception of the end electrochemical cells 2, that is to say the electrochemical cells 2 which are arranged opposite the partitions of the housing 14 in the transverse direction T, the electrical connectors 12 of the electrochemical cells 2 each have a folded end part 42 which participates in delimiting one of the housings 40. Such a folded end part 42 corresponds to a folded portion of the electrical connector 12, which extends substantially at a right angle relative to a longitudinal-transverse plane in which each electrochemical cell 2 mainly extends.

[0055] The folded end portions 42 of the electrical connectors 12 are arranged such that the folded end portion 42 of a given first electrochemical cell 2 is folded at a right angle towards a first side, the folded end portion 42 of the directly adjacent electrochemical cell 2 being folded at a right angle to a second side opposite the first side. Here, the term "first side" means a side facing the first end 34 of the transverse feeder. 32, the “second side” being the one facing the second end 36 of this transverse feeder 32. Two adjacent electrochemical cells 2 therefore have folded end portions 42 oriented towards opposite sides, so as to be juxtaposed with each other to delimit the housing 40. Once these folded end portions 42 are juxtaposed, they are associated with each other by welding at the level of at least one welded zone 44 which allows them to be maintained in relative position, such welded zones 44 being particularly visible in [Fig.6]. The folded end portions 42 here have four welded zones 44, which are aligned in the vertical direction V.

[0056] Each housing 40 receives, between the folded end portions 42 and two adjacent electrochemical cells 2, a spray pipe 38, this spray pipe 38 then allowing spraying of the dielectric fluid as close as possible to the electrical connectors 12. For this purpose, each spray pipe 38 has spray orifices 46 which are particularly visible in [Fig. 4]. Such spray orifices 46 are arranged in a peripheral wall of the spray pipes 38 at the edge of which they are flush. These spray orifices 46 are calibrated orifices. They take the form of rounded holes, as is the case in this [Fig. 4], or even slots extending within the peripheral wall in the vertical direction V as illustrated in [Fig. 2].Whatever the embodiment, the spray orifices 46 are arranged on the peripheral wall opposite the main body 3 of the electrochemical cells, that is to say they are oriented opposite the folded end portions 42 of the electrical connectors 12. Such an orientation makes it possible to direct the dielectric fluid in the direction of these folded end portions 42, jets of dielectric fluid being represented in the form of points in [Fig.3].

[0057] Once the dielectric fluid has been projected onto the folded end portions 42 of the electrical connectors 12, it falls back by gravity onto the bottom wall 20; this bottom wall 20 thus corresponds to a zone for receiving the dielectric fluid. The dielectric fluid is then captured from this bottom wall 20 by the use of the pump of the motor vehicle, and it is conveyed to the reservoir by circulating via the fluid outlet nozzle 28.

[0058] As mentioned previously, the end electrochemical cells 2 do not have a folded end portion 42 participating in delimiting a housing 40. As is particularly visible in FIGS. 3, 5 and 6 in particular, the electrical connectors 12 of the two end electrochemical cells 2 have a plate 48 which is in contact with an electrical terminal 50, 52 of the electrical energy storage device 1 allowing it to be electrically powered. Each plate 48 extends here in the longitudinal direction L, in continuity longitudinal of the electrical connector 12. The electrical energy storage device 1 here comprises a positive electrical terminal 50 arranged in the vicinity of the first end 34 of the transverse feeder 32, and a negative electrical terminal 52 arranged in the vicinity of the second end 34 of this transverse feeder 32, each of these electrical terminals 50, 52 being electrically connected to the electrochemical cells 2 via the plate 48 of the nearest electrochemical cell 2. Alternatively, without departing from the scope of the invention, embodiments could be envisaged in which the positive electrical terminal 50 and the negative electrical terminal 52 are both arranged in the vicinity of the same end 34, 36 of the transverse feeder 32.

[0059] A method of assembling the electrical energy storage device 1 according to the invention will now be described, according to two embodiments which differ in the order of carrying out their steps.

[0060] According to a first embodiment of the assembly method, the latter comprises a step of arranging the electrochemical cells 2 against each other, so that they are aligned in the transverse direction T. The electrical connectors 12 of the electrochemical cells 2 are then folded, during a folding step, in order to form the folded end parts 42. The electrical connectors 12 of two adjacent electrochemical cells 2 are thus folded in the direction of opposite sides, so as to form housings 40 at each of the electrical connection portions 10. The folded end parts 42 are then welded two by two during a welding step, at the welded zones 44 which ensure the mechanical maintenance of the housings 40.Once the folded end portions 42 have been welded, the assembly method comprises a positioning step, during which each of the spray pipes 38 of the cooling system 24 is inserted into a housing 40 thus formed. An assembly formed of the electrochemical cells 2 and the cooling system 24 can then be arranged within the housing 14.

[0061] Conversely, according to a second embodiment of the method for assembling the electrical energy storage device 1, the positioning step occurs as soon as the electrochemical cells 2 are aligned. The housings 40 are not delimited at this stage, this positioning step here consists of arranging each of the spray pipes 38 between the electrical connectors 12 of two adjacent electrochemical cells 2, within the electrical connection portions 10. Once the spray pipes 36 are positioned, during the folding step the electrical connectors 12 are folded so as to form the folded end portions 42 which participate in delimiting the housings 40 by enclosing these spray pipes 38. The folding step is shown in [Fig. 5], the end portions 42 of a housing 40 being partially folded while the other housings 40 are not yet completely delimited. The assembly method continues with the welding step, during which each folded end portion 42 is welded to the folded end portion 42 of an adjacent electrochemical cell 2, forming the welded areas 44. The electrochemical cells 2 and the cooling system 24 can then be arranged within the housing 14 similarly to the first embodiment.

[0062] The present invention thus proposes an electrical energy storage device which has a thermal regulation system, here a cooling system, specifically targeting the areas of the electrical energy storage device which heat up the most during its operation, namely the areas comprising its electrical connectors.

[0063] The present invention cannot, however, be limited to the means and configurations described and illustrated here and it also extends to any equivalent means and configuration as well as to any technically operative combination of such means.

Claims

Claims

1. Electrical energy storage device (1) for a vehicle comprising at least a plurality of electrochemical cells (2), at least two adjacent cells (2) comprising an electrical connection portion (10) connecting the two cells (2), the electrical connection portion (10) and the two cells (2) delimiting a housing (40), the electrical energy storage device (1) comprising a cooling system (24) using dielectric fluid, this cooling system (24) comprising a plurality of spraying pipes (38) intended to project the dielectric fluid, at least one of said pipes (38) extending into the housing (40), the electrical energy storage device (1) comprising a housing (14) within which the cells (2) are arranged,the cooling system (24) being arranged along partitions of the housing (14) and comprising at least one supply line (30) and at least one transverse feeder (32) connected to the supply line (30), the spray lines (38) projecting perpendicularly relative to an extension dimension of the transverse feeder (32), a bottom wall (20) of the housing (14) comprising a dielectric fluid receiving area.,

2. Electrical energy storage device (1) according to the preceding claim, in which the cells (2) comprise electrodes (4) one end of which forms an electrical connector (12) which delimits the housing (40), the electrical connector (12) having a folded end part (42) which delimits the housing (40).

3. Electrical energy storage device (1) according to the preceding claim, in which the folded end portions (42) of an electrical connector (12) of a given cell (2) and of an electrical connector (12) of an adjacent cell (2) are juxtaposed to delimit the housing (40).

4. An electrical energy storage device (1) according to claim 2, wherein the folded end portions (42) comprise at least one welded area (44).

5. An electrical energy storage device (1) according to any preceding claim, wherein an end cell (2) comprises a wafer (48) folded into contact of an electrical terminal (50, 52) of the electrical energy storage device (1).

6. Motor vehicle comprising at least one electrical energy storage device (1) according to any one of the preceding claims.

7. A method of assembling an electrical energy storage device (1) according to any one of claims 1 to 5 in combination with claim 2, comprising a step of positioning at least one of the spray pipes (38) between the electrical connectors (12) of two adjacent cells (2), a step of folding the end portions (42) of the electrical connectors (12) so as to delimit the housing (40), and a step of welding said end portions (42).

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