Battery module, battery module assembly comprising such a module and associated motor vehicle

Abstract

The invention relates to a battery module comprising: - a rear portion (32) having a bottom wall (32A) for contact with a cooling circuit (27), and a rim (32B) running along the bottom wall, the bottom wall having a thickness of less than 3 millimeters; and - a front portion (34) comprising a front wall (34A) bordered by a side wall (34B), said side wall extending towards the rim of the rear portion, the front portion defining with the rear portion a housing for a plurality of battery cells (35), the front and rear portions being joined by wedging said rim of the rear portion and the side wall of the front portion. The invention also relates to a battery module assembly (10) comprising such a module and an associated motor vehicle. Figure for the abstract: Fig. 2

Description

Title of the invention: Accumulator battery module, accumulator battery module assembly comprising such a module and associated motor vehicle Technical field of the invention

[0001] The present invention relates generally to the field of accumulator batteries.

[0002] The invention relates more particularly to a battery module.

[0003] It also relates to a battery module assembly comprising such a module.

[0004] It also relates to a motor vehicle equipped with such an assembly. State of the art

[0005] Electric motor vehicles, including hybrid thermal and electric motor vehicles, are generally equipped with an electric motor powered by a plurality of battery modules.

[0006] In a conventional manner, each battery module consists of a housing which contains a plurality of battery cells.

[0007] Such a battery module is for example known from document EP3637495.

[0008] In this document, the housing has a rear portion surmounted by a cover to define a housing for the battery cells. The rear portion has a U-shaped section, made in one piece, with a bottom wall and two side walls. Two side cover plates complete the side walls of the rear portion to obtain a closed structure.

[0009] The cover cooperates with the rear part by snapping it into place. The entire housing (with the cover) then forms a rigid structure for housing the battery cells.

[0010] A thermally conductive layer is disposed at the bottom wall of the rear part (typically the base of the U of the U-shaped part) so as to allow the cooling of the battery cells.

[0011] However, such a configuration of the rear part does not allow sufficient cooling of the battery cells and therefore does not allow for effective regulation of their temperature. Presentation of the invention

[0012] In order to remedy the aforementioned drawbacks, the present invention proposes to improve the structure of the battery module in order to benefit from efficient cooling of the battery cells included in this module.

[0013] More specifically, the invention proposes a battery module comprising: - a rear section equipped with a bottom wall, intended to be in contact with a cooling circuit, and a rim running along the bottom wall, the bottom wall having a thickness of less than 3 millimeters, and - a front part comprising a front wall bordered by a side wall, said side wall extending towards the edge of the rear part, the front part delimiting with the rear part a housing for a plurality of battery cells, the front part and the rear part being assembled by weaving the said edge of the rear part and the side wall of the front part.

[0014] Thus, according to the present invention, the thickness of the bottom wall of the rear part allows for optimization of heat exchange between the battery cells and the cooling circuit.

[0015] Furthermore, the threading of the front and rear parts makes it possible to form a battery module housing that is sufficiently rigid to contain the battery cells while allowing deformation of this housing so as to contain the expansion of the cells resulting from the thermal stresses generated by the cells themselves during their charging and discharging.

[0016] Thus, these two combined characteristics make it possible to ensure good thermal cooling of the cells, even during the most demanding charging and discharging phases.

[0017] Other advantageous and non-limiting features of the battery module according to the invention, taken individually or in all technically possible combinations, are as follows: - the border has a height of less than 10 millimeters; - the silking includes an assembly of the edge of the rear part and the side wall of the front part by laser welding; - the silking includes an assembly of the edge of the rear part and the side wall of the front part by laser welding, by brazing or by mechanical fastening;

[0018] - the thickness of the bottom wall is between 0.3 and 2 millimeters; - the edge forms an angle of approximately 90 degrees with the back wall; - the rear part is made of an alloy including aluminium; - the front part has greater rigidity than the rear part; - the plurality of accumulator cells is fixed to the bottom wall of the rear part by gluing; - said border is interrupted at the corners; and - the side wall of the front part has, at its corners, elements for fixing to a receiving support of a motor vehicle, said fixing elements being positioned opposite the interrupted corners of the edge of the rear part.

[0019] The invention also relates to a battery module assembly comprising: - a receiving support for a battery module, said receiving support being equipped with a cooling circuit, and - a battery module as previously introduced, the bottom wall of the rear part of said battery module being positioned in contact with said cooling circuit.

[0020] Thermal paste is provided between the cooling circuit and the bottom wall of the rear part of the battery module.

[0021] The receiving support includes means for fixing said battery module, said fixing means being intended to cooperate with the fixing elements of the side wall of the front part of said battery module.

[0022] The invention finally relates to a motor vehicle equipped with such a battery module assembly.

[0023] Of course, the various features, variants, and embodiments of the invention can be combined with one another in various ways, provided they are not incompatible or mutually exclusive. Detailed description of the invention

[0024] The following description with regard to the attached drawings, given by way of non-limiting examples, will make it clear what the invention consists of and how it can be carried out.

[0025] On the attached drawings:

[0026] [Fig-1] represents a schematic view of a motor vehicle equipped with a assembly of battery modules according to the invention; and

[0027] [Fig.2] is an exploded view of the battery module assembly of [Fig.1],

[0028] In [Fig.1], a motor vehicle 1 equipped with a set 10 of battery modules conforming to the invention is shown.

[0029] This motor vehicle 1 is an electrically powered motor vehicle or hybrid equipped with an electric motor. At least one set of 10 battery modules is designed to supply electric current to the electric motor of the motor vehicle 1.

[0030] As shown in Figures 1 and 2, the battery module assembly 10 comprises a battery module receiver 20 (also referred to as "receiving support 20" hereafter) and at least one battery module 30 (also referred to as "module 30" hereafter).

[0031] The receiving support 20 is, for example, here integral with the motor vehicle 1, while the battery module 30 is attached to the receiving support 20.

[0032] Figure 2 shows a schematic exploded perspective view of the elements included in the battery module 30. This module 30 comprises a rear part 32, a front part 34 and a plurality of battery cells 35 (for clarity, only one battery cell 35 is shown in Figure 2).

[0033] In this description, the terms "front" and "rear" are used with respect to the positioning of the element on the receiving support (on which the element in question is attached). The rear of this element refers to the side facing the receiving support on which the element is attached, while the front refers to the side facing away from this receiving support.

[0034] The rear part 32 is intended to be in contact with a cooling circuit 27 present in the receiving support 20.

[0035] The rear part 32 is made of a single piece. For example, it is formed of an alloy comprising aluminum. Alternatively, it can be formed entirely of aluminum.

[0036] As shown in [Fig. 2], the rear portion 32 comprises a bottom wall 32A and a border 32B running along the bottom wall 32A. The border 32B extends forward from the bottom wall 32A. This border 32B forms an angle of approximately 90 degrees with the bottom wall 32A. This 90-degree arrangement helps to minimize the overall size of the rear portion 32 (particularly when it is placed in the receiving support 20).

[0037] The edge 32B has a height of 10 millimeters (mm) or less. Preferably, this height is between 3 and 10 mm. This ensures that there is enough material to assemble the rear part 32 and the front part 34 (the assembly of the rear part 32 and the front part 34 is described below).

[0038] The edge 32B has an overall rectangular profile. Here, as can be seen in [Fig. 2], the edge 32B is interrupted at its corners. This truncated shape at the corners is advantageous for allowing the attachment of the module 30 of rechargeable battery on the receiving support 20.

[0039] Advantageously, according to the invention, the bottom wall 32A has a thickness of less than 3 mm. This thickness of the bottom wall 32A optimizes heat exchange between the battery cells 35 (also referred to as "cells 35" in this description) and the cooling circuit 27. Furthermore, such a thickness reduces the total mass of the battery module 30.

[0040] Preferably, the thickness of the bottom wall 32A is between 0.3 and 2 mm. Even more preferably, it is between 0.7 and 2 mm.

[0041] As shown in [Fig. 2], the front portion 34 of the battery module 30 comprises a front wall 34A bordered by a side wall 34B, extending from the front wall 34A. The side wall 34B of the front portion 34 extends towards the edge 32B of the rear portion 32. In other words, the side wall 34B of the front portion 34 extends from the front wall towards the rear of the battery module 30. By way of illustration, as can be seen in [Fig. 2], the rear portion 32 and the front portion 34 form an inverted shoebox, with the rear portion 32 forming the lid of this box and the front portion 34 the container of this box.

[0042] The front part 34 is, for example, formed from aluminum. It has greater rigidity than the rear part 32.

[0043] To compare the rigidity between the two parts (front and rear), a rigidity test can be performed. During this test, the rear part 32 is, for example, fixed to a test support at a first point, and a mechanical stress is applied to this rear part 32 at a second point located away from the first. The same mechanical stress is applied to the front part 34 fixed to the same test support, with the same distance between the fixing point and the point of application of the stress. The front part 34 is then considered to have greater rigidity than the rear part 32 if, after the application of the aforementioned stress, a greater deformation is observed in the rear part than in the front part 34.

[0044] As shown in [Fig.2], the side wall 34B of the front part has, at its corners, fixing elements 34C to the receiving support 20 of the motor vehicle 1.

[0045] These fixing elements 34C are presented here in the form of columns pierced with a longitudinal opening designed to cooperate with complementary fixing means 22A present on the receiving support 20.

[0046] In order for these fastening elements 34C to cooperate with the means 22C of the receiving support 20, the fastening elements 34C are positioned opposite the interrupted corners of the bottom wall 32B of the rear part 32. In this way, when the module 30 is brought back onto the receiving support, the cooperation between the fixing elements 34C of the front part 34 and the fixing means 22C of the receiving support 20 is not hindered by the rear part 32 of the module 30.

[0047] The front part 34 and the rear part 32 are assembled so as to define a housing for a plurality of battery cells 35 (only one of which is visible in [Fig. 2]). In other words, when assembled, the front part 34 and the rear part 32 form a housing for the battery module 30 which accommodates the plurality of battery cells 35.

[0048] Advantageously according to the invention, the front part 34 and the front part 32 are assembled by threading the edge 32B of the rear part 32 and the side wall 34B of the front part 34.

[0049] In this description, "silk joining" refers to a method of joining two metal walls placed end to end (in line with each other) so as to obtain a final surface that is generally smooth and without any difference in thickness between the two joined walls. Here, the two metal walls are, on the one hand, the edge 32B of the rear part 32 and, on the other hand, the side wall 34B of the front part 34. In other words, here, each portion of the edge 32B of the rear part 32 is joined by silk joining to the corresponding portion (i.e., located opposite the portion of the edge 32B) of the side wall 34B of the front part 34 ([Fig.2]).

[0050] This silk-welding assembly method makes it possible to form a battery module housing that is sufficiently rigid to contain the battery cells while allowing for the expansion resulting from the thermal stresses generated by the cells themselves during their charging and discharging.

[0051] Moreover, this method allows the assembly of a rear part and a front part having different thicknesses and made of different materials while guaranteeing the rigidity and expansion properties essential to a battery module.

[0052] The swaging is facilitated here by the properties of the rim 32B as described above. Indeed, a height of less than 10 mm and an orientation of the rim 32B at 90 degrees with respect to the bottom wall 32A improve the swaging efficiency.

[0053] Preferably here, the joining of the edge 32B of the rear part 32 and the side wall 34B of the front part 34 is carried out by welding. This welding is, for example, laser welding.

[0054] Alternatively, the soldering can correspond to an assembly by brazing or even by mechanical fixing, allowing to obtain a smooth final surface, without difference in thickness between the edge of the rear part and the side wall of the front part.

[0055] The plurality of 35 battery cells is positioned in the housing formed by the assembly of the rear part 32 and the front part 34. The battery cells 35 are, for example, positioned side by side. Here, for example, there are sixteen of them.

[0056] In practice, each cell 35 of the accumulator battery is for example fixed by gluing, by an adhesive element 38 shown in [Fig.2], on the bottom wall 32A of the rear part 32 of the module 30.

[0057] The cells 35 are, for example, flexible-shell cells, that is, cells 35 whose shells can deform during insertion into the housing formed by the front part 34 and the rear part 32, and during charging and discharging. Advantageously, the front part 34 of the battery module 30 helps to contain the deformation of the cells thanks to its properties described above.

[0058] More particularly, the flexible-shell cells 35 have a flexible outer shell which contains inside an electrolyte of organic solution or of a solution based on carbonate and lithium salts.

[0059] This is, for example, a lithium-ion type electrolyte, enclosed in a casing made of a plastic film surrounded by a laminated aluminum film. The plastic film is intended to isolate the electrolyte contained in the cell 35 from the aluminum film.

[0060] These flexible-encased cells 35, well known to those skilled in the art, will not be described in further detail here.

[0061] In order to enable the supply of electric current to the electric motor of the motor vehicle 1, the battery module 30 (formed of the front part 34, the rear part 32 and housing the cells 35) is positioned in the receiving support 20.

[0062] As shown in [Fig. 2], the receiving support 20 has a generally parallelepiped shape. It comprises a rectangular base 22, from the edges of which rise three lateral walls 23, 24, 25 that define a housing 21 for the battery module 30. Here, the two lateral walls 23, 25 are located opposite each other, while opposite the lateral wall 24, the receiving support 20 also has a portion of a lateral wall extending opposite this lateral wall 24 (but which is not shown in [Fig. 2] for the sake of clarity).

[0063] The receiving support 22 includes, at its base 22, a cooling circuit 27. The cooling effect is obtained, for example, from the circulation of water in the cooling circuit 27.

[0064] The cooling circuit 27 is designed to cool, by conduction, the battery cells 35. For this purpose, the bottom wall 32 of the rear part 32 of the module 30 of the accumulator battery is positioned in contact with the bottom 22 of the receiving support 20.

[0065] In order to improve the conduction phenomenon (and therefore the cooling), a thermal paste 26 is positioned between the bottom 22 of the receiving support 20 and the bottom wall 32 of the rear part 32 of the battery module 30. In other words, this thermal paste 26 is positioned between the cooling circuit 27 and the bottom wall 32 of the rear part 32 of the battery module 30 so as to improve the efficiency of the thermal conduction between the cooling circuit 27 and the cells 35 (fixed to the bottom wall 32 of the rear part 32 of the battery module 30).

[0066] This thermal paste 26 prevents the formation of an air gap between the cooling circuit 27 and the cells 35, which improves the conduction phenomenon and therefore the cooling.

[0067] The receiving support 20 is, for example, formed here so as to be watertight against drops of water or dust that could enter the battery module assembly 10. The watertightness is evaluated here according to the IP67 standard in accordance with EN60529.

[0068] To allow the module 30 to be attached to the receiving support 20, the base 22 of the receiving support 20 includes fastening means 22A. These fastening means 22A are designed to cooperate with the fastening elements 34C of the front part 34 of the side wall 34B of the module 30. There are as many fastening means 22A as there are fastening elements 34C on the side wall 34B of the front part 34 of the module 30.

[0069] Here, as shown in [Fig.2], the fastening means 22A are formed by lugs 22A projecting from the bottom 22 of the receiving support 20. These lugs 22A extend from the bottom 22 towards the front of the receiving support 20.

[0070] Each lug 22A cooperates here, by interlocking, with a corresponding longitudinal opening of a column 34C of the side wall 34B of the front part 34.

[0071] The battery module can be attached to the receiving support in a different way. For example, according to an alternative (not shown) variant, the edge can be continuous around the entire perimeter of the back panel (in other words, alternatively, the edge can be continuous, including at its corners). In this case, the back panel of the rear section can have openings, for example, located near the corners of the back panel.

[0072] Thus, the module 30 can be fixed to the receiving support 20 by passing fastening elements (such as screws) through the columns of the side wall of the front part, and then through the openings in the bottom wall of the rear part so as to cooperate with additional fastening means present at the bottom of the receiving support.

[0073] Generally speaking, it should be noted that the dimensions of the front and rear parts of the battery module, as well as those of the receiving support, are adapted according to the number of battery cells housed in the module. In the example described above, the dimensions are adjusted so that the battery module contains 16 cells.

[0074] The embodiment described above relates only to a receiving support associated with a battery module.

[0075] The present invention is applicable, of course, in the case where a plurality of battery modules are included in the motor vehicle. In such a case, a plurality of battery modules can be considered, placed side by side within the motor vehicle. Alternatively, a single receiving support can be considered, accommodating a plurality of battery modules (the battery modules being positioned, for example, side by side on the base of the single receiving support).

[0076] Finally, thanks to the construction of the battery module housing in two separate parts with different characteristics (in materials and thicknesses for example), it is possible to adapt this housing according to the thermal stresses generated by the battery cells in order to contain these expansion effects due to the cells themselves.

[0077] Thanks to the invention, it is therefore possible to implement a compromise in the design of the casing in order to obtain a certain rigidity while ensuring efficient cooling of the cells. Given the thickness characteristics of the rear part of the battery module casing, the heat exchange between the cooling circuit and the cells is optimized, thus enabling efficient cooling of the battery module.

[0078] Finally, this implementation makes it possible to reduce the weight of the battery module, and therefore, advantageously, to reduce its manufacturing cost.

Claims

Claims

1. Accumulator battery module (30) comprising: - a rear part (32) provided with a bottom wall (32A), intended to be placed in contact with a cooling circuit (27), and an edge (32B) running along the bottom wall (32A), the bottom wall (32A) having a thickness of less than 3 millimeters, and - a front part (34) comprising a front wall (34A) bordered by a side wall (34B), said side wall (34B) extending towards the edge (32B) of the rear part (32), the front part (34) delimiting with the rear part (32) a housing for receiving a plurality of accumulator cells (35), the front part (34) and the rear part (32) being assembled by grooving said edge (32B) of the rear part (32) and the side wall (34B) of the front part (34).

2. A battery module (30) according to claim 1, wherein the edge (32B) has a height of less than 10 millimeters.

3. A battery module (30) according to claim 1 or 2, wherein the front portion (34) and the rear portion (32) are assembled by laser welding said edge (32B) of the rear portion (32) and the side wall (34B) of the front portion (34).

4. A battery module (30) according to any one of claims 1 to 3, wherein the thickness of the bottom wall (32A) is between 0.3 and 2 millimeters.

5. A battery module (30) according to any one of claims 1 to 4, wherein the front portion (34) has a greater rigidity than the rear portion (32).

6. A battery module (30) according to any one of claims 1 to 5, wherein said border (32B) is interrupted at corners.

7. A storage battery module (30) according to claim 6, wherein the side wall (34B) of the front part (34) has, at its corners, fixing elements (34C) for attachment to a receiving support (20) of a motor vehicle (1), said fixing elements (34C) being positioned opposite the interrupted corners of the edge (32B) of the rear part (32).

8. An accumulator battery module assembly (10) comprising: - a support (20) for receiving a battery module (30) of accumulators, said receiving support (20) being provided with a cooling circuit (27), and - an accumulator battery module (30) according to any one of claims 1 to 7, the bottom wall (32A) of the rear part (32) of said accumulator battery module (30) being positioned in contact with said cooling circuit (27).

9. An accumulator battery module assembly (10) according to claim 8 taken in dependence on claim 7, wherein the receiving support (20) comprises fixing means (22A) for said accumulator battery module (30), said fixing means (22A) being intended to cooperate with the fixing elements (34C) of the side wall (34B) of the front part (34) of said accumulator battery module (30).

10. Motor vehicle (1) comprising an accumulator battery module assembly (10) according to claim 8 or 9.

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