Method for assembling a block of electric accumulator batteries

Abstract

A method for assembling a block (1) of electric storage batteries, comprising the following steps: a tray (3) defining a plurality of open compartments (5) is provided; at least one set of cells (13) is provided, comprising a plurality of electrochemical cells (15) and a plurality of spacers (17) separating the electrochemical cells (15) from one another; said at least one set of cells (13) is inserted into one of said compartments (5); characterized in that compressible spacers (17) are provided, and in that said at least one set of cells (13) is compressed so that the compressed at least one set (13) can be inserted into one of said compartments (5), such that said compressed at least one set (13) remains compressed. Abstract figure: Figure 1

Description

Title of the invention: Method for assembling a block of electric accumulator batteries.

[0001] The present invention relates to a method of assembling a battery pack of electric accumulators for an electric or hybrid motor vehicle, as well as a battery pack obtained by this method.

[0002] Electric or hybrid motor vehicles comprise a block of electric accumulator batteries comprising several sets of electrochemical cells for storing electrical energy, which must be maintained under a certain compressive force.

[0003] A known type of battery pack, presented in document FR3086804, comprises electrochemical cells and a frame comprising side members arranged in a longitudinal direction and cross members arranged in a transverse direction to hold the cells. The frame thus forms housings each receiving a set of cells not fixed to each other and held in a fixed position by the clamping of the side members and cross members of the frame.

[0004] The assembly of the battery pack presented is done by positioning the crosspieces then the first side member. In each space formed between two crosspieces, a set of cells is placed against the first side member then the second side member is placed and the previous operation is repeated. The installation of each side member is carried out by performing a transverse clamping on the juxtaposed sets of cells.

[0005] However, throughout their use, not only does the volume of the electrochemical cells vary between 5 and 20% with each charge and discharge cycle, in a manner comparable to breathing, but in addition the volume of the cells increases progressively throughout their life, in a manner comparable to swelling. If this double variation in volume, breathing and swelling, is not controlled, then this can lead to premature aging of the electrochemical cells as well as safety problems such as risks of battery fire.

[0006] But the holding system used in document FR3086804 has the sole objective of applying a certain pressure on the cells during assembly. It does not allow this double variation in the volume of the cells to be controlled. In addition, the total space occupied by the battery is increased as well as the total mass of the battery since new elements are added to hold the cells in a fixed position. This reduces the energy density of the battery and consequently reduces the autonomy of the vehicle equipped with this battery.

[0007] Finally, the proposed arrangement of the cells requires in the event of an incident on certain cells to completely dismantle the support system which increases the cost of repairs.

[0008] There is therefore a need for electric storage batteries which make it possible to control the double variation in volume of the cells and to maintain a certain pressure on them.

[0009] For this purpose, a method of assembling a block of electric accumulator batteries is proposed, comprising the following steps: - a locker is provided defining a plurality of open housings; - at least one set of cells comprising a plurality of electrochemical cells and a plurality of spacers separating the electrochemical cells from each other; - said at least one set of cells is inserted inside one of said housings. The interlayers are compressible and said at least one set of cells is compressed to be able to insert the at least one compressed set inside one of said housings so that said at least one compressed set remains compressed.

[0010] Thus, one of the characteristics of the invention lies in the use of compressible interlayer making it possible to regulate the variation in volume of the cells during their use.

[0011] Indeed, when the volume of the cells increases, that of the compressible interlayers decreases so as to maintain a constant volume in the set of cells while limiting the increase in volume of the set of cells.

[0012] In addition, the rack used in the invention makes it possible to keep the cells and the interlayers compressed by applying a certain pressure. Advantageously, spacers made of elastomer, polymer foam or silicone are provided.

[0014] Advantageously, an open housing is further provided and said at least one compressed assembly is inserted into the housing before inserting said housing inside one of said housings.

[0015] The use of an open housing makes it possible to insert the set of cells into an intermediate element to obtain a first compression of the set and to keep it compressed in the housing before inserting it into the housing.

[0016] The open case also allows the set of cells to be easily reused. In fact, in the prior art, the cells were removed by completely dismantling the case. However, in accordance with the invention, the case can be recovered to reinstall it in another battery, for example.

[0017] In addition, there was no object to keep the cells close to each other. others. So, when the battery pack was dismantled, the cells had to be recovered one by one and reinstalled in another battery for reuse in a second life.

[0018] Advantageously, an open case is provided having walls with a thickness less than or equal to 1 millimeter. The use of a thin wall allows for good thermal conduction allowing the thermal energy produced by the set of cells to escape more easily. The thin walls also make the case deformable. Finally, the thin walls of the open case allow the use of a battery with a constant or reduced volume compared to the prior art but also a lighter battery.

[0019] Advantageously, an open case is provided having at least two opposite handles allowing the case to be easily installed and lifted.

[0020] Preferably, a locker is provided comprising a rigid receiving tray.

[0021] Advantageously, a locker is provided further comprising transverse walls and rigid longitudinal walls intersected so as to form a plurality of housings, said intersecting walls being inserted into the rigid receiving tray.

[0022] The provided rack is assembled in one go so that the intersecting longitudinal and transverse walls form at least one housing. The walls and the receiving tray being rigid, they allow the set of cells to be kept compressed.

[0023] In addition, the cell assembly can be retrieved through the opening of the locker and it is not necessary to completely disassemble the walls to reuse, replace or retrieve the cell assembly.

[0024] Advantageously, a gripping tool is used to insert the housing inside one of said housings.

[0025] The gripping tool makes it possible to grip and insert the housing comprising the compressed set of cells.

[0026] The gripping tool can be installed in an automatic system so that the assembly can be automated.

[0027] Preferably, the gripping tool comprises at least two opposite clamps, adapted to compress the housing in order to be able to engage it inside one of said housings.

[0028] Advantageously, the gripping tool further comprises at least two opposite hooks adapted to engage in the handles of the housing.

[0029] Another object of the invention is a block of electric accumulator batteries comprising a rack defining a plurality of open housings and at least one set of cells comprising a plurality of electrochemical cells and a plurality of spacers separating the electrochemical cells from each other, said at least one set of cells being inside one of said housings. The in intercalaries are compressible and said set of cells is compressed by the housing.

[0030] Other features and advantages of the invention will emerge from reading the description given below of several particular embodiments of the invention, given for informational but non-limiting purposes, with reference to the appended drawings in which

[0031] [Fig-1] is a schematic perspective view of a battery pack according to the invention;

[0032] [Fig.2a] is a schematic perspective view of a first element of the block of the [Fig.l] according to the invention;

[0033] [Fig.2b] is a schematic perspective view of a second element of the block of the [Fig.l] according to the invention;

[0034] [Fig.2c] is a schematic perspective view of the assembly of the elements of the [Fig.2a] and [Fig.2b] according to the invention;

[0035] [Fig.3] is a schematic perspective view of the assembly of the elements of the [Fig.2a] and [Fig.2b] different according to the invention;

[0036] [Fig.4] is a schematic perspective view of a third element of the block of the [Fig.l] according to the invention;

[0037] [Fig.5] is a schematic perspective view of a battery pack according to another embodiment of the invention;

[0038] [Fig.6] is a schematic perspective view of a fourth element of the block of the [Fig.5] according to another embodiment of the invention;

[0039] [Fig.7] is a schematic perspective view of the assembly of the elements of the [Fig.6] and [Fig.4] according to another embodiment of the invention;

[0040] [Fig.8] is a schematic perspective view of the assembly of the elements of the [Fig.6] and [Fig.4] according to another embodiment of the invention;

[0041] The invention relates to a method for assembling a battery pack for electric storage batteries. The invention also relates to a battery pack for electric storage batteries obtained in accordance with the described assembly method.

[0042] [Fig.l] illustrates a block 1 of electric accumulator batteries comprising several sets of cells obtained according to the assembly method according to the invention.

[0043] With reference to [Fig.l], a battery pack 1 comprises a rack 3 having nine open housings 5. The rack 3 comprises a rigid receiving tray 7 as well as rigid transverse 9 and longitudinal 11 walls. The transverse 9 and longitudinal 11 walls are intersected so as to form the nine housings 5.

[0044] The locker 3 can be of any shape. Preferably, it is parallelepiped in shape.

[0045] The number of housings 5 ​​is not limited. It mainly depends on the desired battery capacity.

[0046] The transverse 9 and longitudinal 11 walls will typically be made of a lightweight material and if possible recycled in whole or in part, for example metal such as aluminum or recycled plastic, possibly loaded with glass fibers.

[0047] The battery pack 1 further comprises a single cell assembly 13 inserted into a housing 5. The cell assembly 13 comprises a plurality of electrochemical cells 15 as well as a plurality of spacers 17 separating the electrochemical cells from each other. It will be described in more detail below.

[0048] Just as for the housing 5, the number of sets 13 is not limited. It depends mainly on the capacity of the battery and the desired number of cells. In [Fig.l], the rack 3 is capable of receiving nine sets 13 of cells adapted to be inserted into the nine housings 5 ​​respectively.

[0049] Referring to [Fig.4], for example, the electrochemical cells 15 are pocket-type cells and they have a parallelepiped shape with flexible packaging. The cells 15 are placed successively alternately with interlayers 17.

[0050] The interlayers 17 are compressible and have the same shape as the cells 15. For example, they are made of polymer foam, for example polyurethane foam or polyethylene foam. They can also be made of silicone or elastomer such as polyurethane or polyether. Finally, they can be made of a combination of polymer foam and elastomer.

[0051] The compressible interlayers 17 make it possible to manage the volume variations of the electrochemical cells 15 during charge / discharge cycles or during aging. To maintain a constant volume, when the volume of the cells increases, the volume of the interlayers decreases while when the volume of the cells decreases, the volume of the interlayers increases. The interlayers also make it possible to limit pressure variations during cell volume variations by applying the desired pressure to the cells.

[0052] According to the method of assembling the accumulator battery block 1, in accordance with the invention, a rack 3 is first provided.

[0053] The provided locker 3 comprises a rigid receiving tray 7 as illustrated in [Fig.2a].

[0054] Optionally and not shown, the receiving tray 7 incorporates a cooling network cooling plate, or a cooling plate, to cool the battery pack 1 when it heats up.

[0055] The provided locker 3 further comprises rigid transverse 9 and longitudinal 11 walls as illustrated in [Fig.2b]. The walls 9 have first notches 19 and the walls 11 have second notches 20. The first and second notches 19 and 20 are separated so as to obtain compartments of the same volume. The spacing between the first notches 19 may however be different from the spacing between the second notches 20 so as to obtain housings 5 ​​of rectangular shape for example.

[0056] The first notches 19 extend over the width of the walls 9 from a lateral edge 32. They extend so as to cover at least one third and at most three quarters of the width. Similarly, the second notches 20 extend over the width of the walls 11 from a lateral edge 33. They extend so as to cover at least one third and at most three quarters of this width.

[0057] The first and second notches 19 and 20 of the walls 9 and 11 allow them to be assembled by interlocking by intersecting them so as to form a grid and therefore a plurality of housings 5.

[0058] The number of notches on each wall depends on the number of housings desired. In [Fig.2b], the walls 9 each have two first notches 19 and the walls 11 each have two second notches 20.

[0059] The assembly of the walls 9 and 11 is therefore easy and allows the walls to be held together. Disassembly is also easier.

[0060] Then, with reference to [Fig.2c], the walls 9 and 11 are positioned in the receiving tray 7 by screwing them onto the tray 7 using, for example, vertical through screws. The screws are screwed vertically into the thickness of the walls 9 and 11 and then into the bottom of the tray 7.

[0061] The pressure forces in the transverse directions will thus be transmitted by the assembly of walls 9 and 11 and finally taken up by the tank 7.

[0062] The spacers 17 serve to compensate for variations in volume of the cells 15 while the walls 9 and 11 serve to hold the spacers 17 which are compressed during assembly and which tend to vary in volume under the effect of the pressure exerted by the cells 15.

[0063] When all the housings 5 ​​comprise a set 13 of cells 15, then the walls 9 and 11 located opposite the large faces of the cells 15 undergo a pressure force, but this force is balanced on the other side of the crosspiece by the entire neighboring housing 5. Except for the external walls 9 and 11, which rest on the tray 7. In this case, the pressure forces pass through these walls and are taken up by the tray 7. The walls therefore do not need to be very strong, as long as they resist crushing, nor do they need to be securely fixed to the tray 7.

[0064] The walls must essentially resist the compression forces between their two lateral faces, i.e. crushing.

[0065] The walls can be equipped with vertical metal inserts 21 which will allow them to be fixed to the tray 7 using a screw. These can also be simple drillings in the thickness of the wall, without inserts. This solution is preferred to a gluing solution, because the screwed assembly is more easily disassembled, which is an advantage for recycling by facilitating the separation of its components to be treated.

[0066] In another embodiment, the walls 9 and 11 have grooves 33 so that there are grooves 33 in each housing 5. The walls 9 and 11 respectively have two wide grooves per wall which are made transversely.

[0067] Optionally, with reference to [Fig.3], on the bottom of the tray 7 and in each housing 5, a thermal paste 22 is preferably placed, the purpose of which is to improve the thermal conduction between the cells 15 and the tray 7.

[0068] Then, according to the assembly method, with reference to [Fig.4], a plurality of electrochemical cells 15 and a plurality of compressible interlayers 17 are provided. Then they are assembled to form a set 13 of cells so that the electrochemical cells 15 are separated from each other by the interlayers 17.

[0069] The cell assembly 13 is inserted into a housing 5. For this, the assembly 13 is compressed to be able to insert the compressed assembly 13 inside the housing 5 whereby the compressed assembly 13 remains compressed.

[0070] This step is repeated until all the housings 5 ​​are filled.

[0071] In another embodiment, with reference to [Fig. 5], a single set of cells 13 is installed in an open case 23 which is then installed in a housing 5.

[0072] Preferably, the open case 23 has walls with a thickness less than or equal to 1 millimeter so as to have lightweight cases which do not increase the weight of the battery. The use of a thin wall also allows for good thermal conduction thanks to which the thermal energy produced by the set of cells is evacuated more easily.

[0073] According to another embodiment of the assembly method, after having provided a compartment 3, an open box 23 is provided. According to [Fig.5] nine boxes 23 are provided, one for each housing 5.

[0074] Preferably, the housings 23 are made of stamped aluminum sheet. Other materials are possible, such as steel. However, preference will be given to lightweight materials that are good thermal conductors, inexpensive and have a low environmental footprint. The preferred production of the housings 23 by stamping is an inexpensive process, which can be used here because the shape is simple and there is no need for the part to strongly resist mechanical stresses.

[0075] With reference to [Fig.6], a thermal paste 24 is deposited at the bottom of the case 23 to improve the thermal conduction between the cells 15 and the bottom of the case 23.

[0076] An advantage here is that the thermal conduction of the bottom of the housing 23 is improved, making it even easier to evacuate the energy produced by the cells to cool them.

[0077] Then, with reference to [Fig.7], the set of cells 13 is compressed by compressing the inserts 17 and then the compressed set 13 is inserted into the housing 23 so that the set of cells 13 remains compressed by the housing before their insertion into the housings 5.

[0078] Finally, the housing 23 is inserted into a housing 5 or the set 13 of cells compressed into the housing 5.

[0079] The housing 23 has at least two opposite handles. Preferably, as illustrated in [Fig. 8], the housing 23 has four opposite handles 25 to facilitate their handling during installation and uninstallation of the housing 23 in the housing 5.

[0080] As shown in [Fig.8], a gripping tool 27 is used to insert the housing 23 into the housing 5.

[0081] The gripping tool 27 has two different functions.

[0082] Its first function is to compress the deformable housing 23 so that it can be engaged in the housing. For this, the gripping tool 27 comprises at least two opposite clamps 29 which grip and compress the housing 23 as well as the set of cells 15.

[0083] The grippers of the gripping tool coincide with grooves 33 provided in the transverse 9 and longitudinal 11 walls, which allows them to be easily inserted and removed.

[0084] During assembly, optionally, it is ensured that the cells 15 are in good contact with the thermal paste 24 at the bottom of the case 23, and that the bottom of the case 23 is in good contact with the thermal paste 22 placed at the bottom of the tray 7.

[0085] The second function of the gripping tool is to take the housing 23 to insert it into the housing 5. For this, the gripping tool 27 comprises at least two opposite hooks 31 adapted to engage in the handles 25 of the housing 23. The gripping tool also makes it possible to hold the walls of the housing 23 which can deform under the effect of the pressure of the compressed set of cells 13.

[0086] [Fig.8] illustrates the gripping tool comprising four hooks 31 as well as four pairs of clamps 29 applied to the four walls of the housing 23.

[0087] The hooks 31 are adapted to engage in the handles 25.

[0088] Once inserted, the walls 9 and 11 serve to hold the boxes 23, which tend to swell under the effect of the pressure exerted by the spacers 17 which are compressed during the assembly of cells 13 in the boxes 23.

[0089] When all the housings are fitted with a box, the forces are balanced on both sides of the walls by the baskets and / or by the walls of the tray 7. The characteristic assembly The characteristics of this embodiment thus make it possible to generate little mechanical stress on the walls 9 and 11.

[0090] The assembly of block 1 is therefore made up of very few parts, it is easily disassembled, light, compact and inexpensive. The boxes can, after extraction from their compartments, be easily reused in a second life by placing them in individual compartments. In this way, the assembly has a reduced environmental footprint.

Claims

Claims

1. Method for assembling a block (1) of electric accumulator batteries, comprising the following steps: - providing a rack (3) defining a plurality of open housings (5); - providing at least one set of cells (13) comprising a plurality of electrochemical cells (15) and a plurality of spacers (17) separating the electrochemical cells (15) from each other; - inserting said at least one set of cells (13) inside one of said housings (5); characterized in that the spacers (17) are compressible, and in that compressing said at least one set of cells (13) to be able to insert the at least one compressed set (13) inside one of said housings (5), so that said at least one compressed set (13) remains compressed.

2. Assembly method according to claim 1, characterized in that spacers (17) made of elastomer, polymer foam or silicone are provided.

3. Assembly method according to claims 1 or 2, characterized in that an open housing (23) is further provided and in that said at least one compressed assembly (13) is inserted into the housing (23) before inserting said housing (23) inside one of said housings (5).

4. Assembly method according to any one of claims 1 to 3, characterized in that an open housing (23) is provided having walls with a thickness less than or equal to 1 millimeter.

5. Assembly method according to any one of claims 1 to 4, characterized in that an open housing (23) is provided having at least two opposite handles (25).

6. Assembly method according to any one of claims 1 to 5, characterized in that a rack (3) is provided comprising a rigid receiving tray (7).

7. Assembly method according to any one of claims 1 to 6, characterized in that a locker (3) is provided, further comprising rigid transverse (9) and longitudinal (11) walls intersecting with so as to form a plurality of housings (5), said intersecting walls (9, 11) being inserted into the rigid receiving tray (7).

8. Assembly method according to claim 3 and 7, characterized in that a gripping tool (27) is used to insert the housing (23) inside one of said housings (5).

9. Assembly method according to claim 8, characterized in that the gripping tool (27) comprises at least two opposite clamps (29), adapted to compress the housing (23) in order to be able to engage it inside one of said housings (5).

10. Assembly method according to claim 8 or 9, characterized in that the gripping tool (27) further comprises at least two opposite hooks (31) adapted to engage in the handles (25) of the housing.

11. Block (1) of electric accumulator batteries comprising a rack (3) defining a plurality of open housings (5) and at least one set of cells (13) comprising a plurality of electrochemical cells (15) and a plurality of spacers (17) separating the electrochemical cells (15) from each other, said at least one set of cells (13) being inside one of said housings (5), said block (1) is characterized in that the spacers (17) are compressible and in that said at least one set of cells (13) is compressed by the housing (5).

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