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 include a battery pack of electric accumulators comprising several sets of electrochemical cells for storing electrical energy, which must be kept under a certain compressive force.

[0003] A known type of battery pack, shown in document FR3086804, comprises electrochemical cells and a frame including longitudinal members and transverse members for retaining the cells. The frame thus forms compartments, each receiving a set of cells not fixed to each other and held in a fixed position by clamping the frame's longitudinal members and transverse members.

[0004] The battery pack shown is assembled by positioning the cross members and then the first longitudinal member. In each space formed between two cross members, a set of cells is placed against the first longitudinal member, then the second longitudinal member is placed and the previous operation is repeated. Each longitudinal member is installed by applying transverse clamping to the adjacent sets of cells.

[0005] However, throughout their use, not only does the volume of electrochemical cells vary between 5 and 20% with each charge and discharge cycle, in a manner comparable to respiration, but the volume of the cells also gradually increases throughout their lifespan, in a manner comparable to swelling. If this dual volume variation, respiration and swelling, is not controlled, it can lead to premature aging of the electrochemical cells as well as safety problems such as the risk of battery fires.

[0006] However, the holding system used in document FR3086804 has the sole purpose of applying a certain pressure to the cells during assembly. It does not allow for control of this dual variation in cell volume. Furthermore, the total space occupied by the battery is increased, as is 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 decreases the range 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, the complete dismantling of the support system, which increases the cost of repairs.

[0008] There is therefore a need for electrical accumulator batteries to control the double variation of the volume of the cells and to maintain a certain pressure on them.

[0009] To this end, a method for assembling a block of electric accumulator batteries is proposed, comprising the following steps: - a locker defining a plurality of open housing units is provided; - at least one set of cells is provided, comprising a plurality of electrochemical cells and a plurality of interlayers separating the electrochemical cells from each other; - at least one set of cells is inserted inside one of the said dwellings. The interlayers are compressible and said at least one set of cells is compressed in order 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 allowing 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 intercalated cells 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.

[0013] Advantageously, interlayers made of elastomer, polymer foam or silicone are provided.

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

[0015] The use of an open case allows the cell assembly to be inserted into an intermediate element to obtain a first compression of the assembly and to keep it compressed in the case before inserting it into the housing.

[0016] The open casing also allows for easy reuse of the entire cell assembly. Indeed, in the prior art, the cells were removed by completely disassembling the compartment. However, according to the invention, the casing can be recovered and reinstalled in another battery, for example.

[0017] Furthermore, no object was used to keep the cells close together. Thus, when the battery pack was disassembled, the cells had to be retrieved one by one and reinstalled in another battery for reuse in a second life.

[0018] Advantageously, an open casing is provided with walls of a thickness of 1 millimeter or less. The use of thin walls allows for good thermal conductivity, enabling the thermal energy produced by the cell assembly to dissipate more easily. The thin walls also make the casing deformable. Finally, the thin walls of the open casing allow for the use of a battery with a constant or reduced volume compared to the prior art, as well as a lighter battery.

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

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

[0021] Advantageously, a compartment is provided comprising, in addition, transverse walls and rigid longitudinal interlockings so as to form a plurality of housings, said interlocking walls being inserted into the rigid receiving tray.

[0022] The supplied compartment is assembled in one piece so that the interlocking longitudinal and transverse walls form at least one compartment. The rigidity of the walls and the receiving tray allows the entire cell assembly to remain compressed.

[0023] In addition, the cell assembly can be retrieved by opening the locker and it is not necessary to completely dismantle 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 allows the housing containing the compressed cell assembly to be grasped and inserted.

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

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

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

[0029] Another object of the invention is a battery pack of electric accumulators comprising a compartment defining a plurality of open compartments and at least one set of cells comprising a plurality of electrochemical cells and a plurality of interlayers separating the electrochemical cells from each other, said at least one set of cells being inside one of said housings. The interlayers are compressible and said set of cells is compressed by the housing.

[0030] Other features and advantages of the invention will become apparent from the following description of several particular embodiments of the invention, given by way of example but not limitation, with reference to the accompanying drawings in which:

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

[0032] [Fig.2a] is a schematic perspective view of a first element of the block of the [Fig.1] according to the invention;

[0033] [Fig.2b] is a schematic perspective view of a second element of the block of the [Fig.1] 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] are different according to the invention;

[0036] [Fig.4] is a schematic perspective view of a third element of the block of the [Fig.1] according to the invention;

[0037] [Fig.5] is a schematic perspective view of a battery pack according to another method of implementing 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 of electrical accumulators. The invention also relates to a battery pack of electrical accumulators obtained according to the assembly method described.

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

[0043] With reference to [Fig. 1], a battery block 1 comprises a compartment 3 having nine open slots 5. The compartment 3 includes a rigid receiving tray 7 and rigid transverse walls 9 and longitudinal walls 11. The transverse walls 9 and longitudinal walls 11 are interlocked to form the nine slots 5.

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

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

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

[0047] The battery block 1 further comprises a single set 13 of cells inserted into a housing 5. The set 13 of cells comprises a plurality of electrochemical cells 15 and a plurality of spacers 17 separating the electrochemical cells from one another. It will be described in more detail below.

[0048] Just as with the housing 5, the number of sets 13 is not limited. It depends mainly on the battery capacity and the desired number of cells. In [Fig. 1], the compartment 3 is suitable for receiving nine sets 13 of cells adapted to be inserted into the nine respective housings 5.

[0049] With reference to [Fig. 4], for example, the electrochemical cells 15 are pocket-type cells and have a parallelepiped shape with a flexible packaging. The cells 15 are placed successively in alternation 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, such as polyurethane foam or polyethylene foam. They can also be made of silicone or an elastomer such as polyurethane or polyether. Finally, they can be made of a combination of polymer foam and elastomer.

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

[0052] According to the assembly method of the block 1 of accumulator batteries, according to the invention, a compartment 3 is first provided.

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

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

[0055] The supplied compartment 3 further comprises rigid transverse walls 9 and longitudinal walls 11 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 to obtain compartments of equal volume. The spacing between the first notches 19 may, however, be different from the spacing between the second notches 20 to obtain rectangular compartments 5, for example.

[0056] The first notches 19 extend across the width of the walls 9 from a lateral edge 32. They extend so as to cover a minimum of one-third and a maximum of three-quarters of the width. Similarly, the second notches 20 extend across the width of the walls 11 from a lateral edge 33. They extend so as to cover a minimum of one-third and a maximum of 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 them so as to form a grid and therefore a plurality of housing 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 walls 9 and 11 is therefore easy and allows the walls to be held together. Disassembly is also easier.

[0060] Next, 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 through the thickness of the walls 9 and 11 and then into the bottom of the tray 7.

[0061] The pressure forces along the transverse directions will thus be transmitted by the wall assembly 9 and 11 and finally taken up by the tray 7.

[0062] The spacers 17 serve to compensate for the volume variations of the cells 15 while the walls 9 and 11 serve to maintain 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 are subjected to a pressure force, but this force is balanced on the other side of the cross member by the entire adjacent housing 5. Except for the external walls 9 and 11, which rest on the tray 7. In this case, the pressure forces are transmitted through these walls and absorbed 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 compressive forces between their two lateral faces, i.e., crushing.

[0065] The walls can be fitted with vertical through-hole metal inserts 21 which allow them to be fixed to the container 7 via a screw. Alternatively, they can be simply drilled through the thickness of the wall, without inserts. This solution is preferred to a bonding solution because the screwed assembly is easier to disassemble, which is an advantage for recycling by facilitating the separation of its components for processing.

[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 have respectively 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 thermal conduction between the cells 15 and the tray 7.

[0068] Next, 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. They are then assembled to form a set 13 of cells such 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 so that the compressed assembly 13 can be inserted inside the housing 5, whereby the compressed assembly 13 remains compressed.

[0070] This step is repeated until all 5 housing units 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 casing 23 has walls with a thickness of 1 millimeter or less, resulting in lightweight casings that do not increase the weight of the battery. The use of thin walls also allows for good thermal conductivity, enabling the heat energy produced by the cell assembly to dissipate more easily.

[0073] According to another embodiment of the assembly method, after providing a compartment 3, an open housing 23 is provided. According to [Fig. 5], nine housings 23 are provided, one for each compartment 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 method of manufacturing the housings 23 by stamping is a inexpensive process, which can be used here because the shape is simple and there is no need for the part to be highly resistant to mechanical stresses.

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

[0076] One advantage here is that the thermal conduction of the bottom of the case 23 is improved, allowing the energy produced by the cells to be evacuated even more easily to cool them.

[0077] Next, with reference to [Fig.7], the cell assembly 13 is compressed by compressing the interlayers 17 and then the compressed assembly 13 is inserted into the housing 23 so that the cell assembly 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 compressed cells is inserted into the housing 5.

[0079] The housing 23 has at least two opposing handles. Preferably, as illustrated in [Fig.8], the housing 23 has four opposing handles 25 to facilitate their handling during the installation and removal 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 inserted into the housing. For this purpose, the gripping tool 27 comprises at least two opposing grippers 29 which grasp and compress the housing 23 as well as the cell assembly 15.

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

[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 hold of the housing 23 and insert it into the housing 5. For this purpose, the gripping tool 27 includes at least two opposing hooks 31 adapted to engage with the loops 25 of the housing 23. The gripping tool also helps to hold the walls of the housing 23 which may deform under the effect of the pressure of the compressed cell assembly 13.

[0086] Fig. 8 illustrates the gripping tool comprising four hooks 31 and 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 housing 23, which tend to swell under the effect of the pressure exerted by the interlayers 17 which are compressed during the assembly of cells 13 in the housings 23.

[0089] When all the compartments are filled with a housing, the forces are balanced on both sides of the walls by the baskets and / or by the walls of the tray 7. The assembly characteristic of this embodiment thus makes it possible to generate little mechanical stress on the walls 9 and IL

[0090] The assembly of block 1 therefore consists of very few parts, is easily disassembled, lightweight, compact, and inexpensive. The housings, after being removed from their compartments, can be easily reused by placing them in individual compartments. In this respect, the assembly has a reduced environmental footprint.

Claims

Demands

1. Method of assembling a block (1) of electric accumulator 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 each other; - said at least one set of cells (13) is inserted inside one of said compartments (5);the interlayers (17) are compressible, and said at least one set of cells (13) is compressed in order 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. An open case (23) is further provided and said at least one compressed set (13) is inserted into the case (23) before inserting said case (23) inside one of said housings (5), characterized in that the open case (23) has walls of a thickness less than or equal to 1 millimeter.

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 case (23) is provided having at least two opposing handles (25).

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

5. Assembly method according to any one of claims 1 to 4, characterized in that a compartment (3) is provided, further comprising rigid cross-sectional (9) and longitudinal (11) walls interlaced so as to form a plurality of housings (5), said cross-sectional walls (9, 11) being inserted into the rigid receiving tray (7).

6. Assembly method according to claim 1 and 5, characterized in that a gripping tool (27) is used to insert the housing (23) inside one of said housings (5).

7. Assembly method according to claim 6, characterized in that the gripping tool (27) comprises at least two opposing grippers (29), adapted to compress the housing (23) in order to engage it inside one of said housings (5).

8. Assembly method according to claim 6 or 7, characterized in that the gripping tool (27) further comprises at least two opposing hooks (31) adapted to engage in the handles (25) of the housing.

9. A battery pack (1) comprising a compartment (3) defining a plurality of open slots (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 one another, said at least one set of cells (13) being inside one of said slots (5), the spacers (17) being compressible, and said at least one set of cells (13) being compressed by the slot (5), said battery pack (1) further comprises an open casing (23) into which said at least one set (13) is inserted, compressed within the casing (23) before inserting said casing (23) inside one of said slots (5), characterized in that the open casing (23) has walls of a thickness less than or equal to 1 millimeter.

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