FR3139672A1 - Accumulator battery module, accumulator battery module assembly comprising such a module and associated motor vehicle - Google Patents

Abstract

The invention relates to a storage battery module comprising: - a rear part (32) provided with a bottom wall (32A), intended to be brought into contact with a cooling circuit (27), and a border (32B) running along the bottom wall, the bottom wall having a thickness less than 3 millimeters, and- a front part (34) comprising a front wall (34A) bordered by a side wall (34B), said side wall s 'extending towards the edge of the rear part, the front part delimiting with the rear part a housing for receiving a plurality of accumulator cells (35), the front part and the rear part being assembled by countersinking said edge of the rear part and the side wall of the front part. The invention also relates to a storage battery module assembly (10) comprising such a module and an associated motor vehicle. Figure for abstract: Fig. 2

Description

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

The present invention relates generally to the field of storage batteries.

The invention relates more particularly to a storage battery module.

It also relates to a battery module assembly comprising such a module.

It also concerns a motor vehicle equipped with such an assembly.

State of the art

Electrically powered motor vehicles, including hybrid thermal and electric vehicles, are generally equipped with an electric motor supplied with current by a plurality of storage battery modules.

Typically, each storage battery module is formed of a housing which houses a plurality of storage battery cells.

Such a storage battery module is for example known from document EP3637495.

In this document, the housing has a rear part topped with a cover so as to define a housing for the accumulator cells. The rear part has a U-shaped part, made of a single piece, with a bottom wall and two side walls. Two side cover plates make it possible to complete the side walls of the rear part so as to obtain a closed structure.

The cover engages with the rear part by snapping. The entire housing (with the cover) then forms a rigid structure to accommodate the accumulator battery cells.

A thermally conductive layer is provided 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 accumulator battery cells.

However, such a configuration of the rear part does not allow sufficient cooling of the battery cells and therefore does not allow effective regulation of their temperature.

Presentation of the invention

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

More particularly, the invention provides an accumulator battery module comprising:
- a rear part provided with a bottom wall, intended to be placed in contact with a cooling circuit, and with a border 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 receiving a plurality of accumulator cells,
the front part and the rear part being assembled by grooving said edge of the rear part and the side wall of the front part.

Thus, according to the present invention, the thickness of the bottom wall of the rear part makes it possible to optimize the heat exchanges between the accumulator battery cells and the cooling circuit.

In addition, the assembly by grooving of the front part and the rear part makes it possible to form a sufficiently rigid accumulator battery module housing to contain the accumulator battery cells while allowing deformation of this housing so as to contain the expansion of the cells resulting from the thermal forces generated by the cells themselves during their charging and discharging.

Thus, these two characteristics combined ensure good thermal cooling of the cells, even during the most demanding charging and discharging phases.

Other advantageous and non-limiting characteristics of the storage 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 joist includes an assembly of the border of the rear part and the side wall of the front part by laser welding;
- the joist includes an assembly of the edge of the rear part and the side wall of the front part by laser welding, brazing or mechanical fixing;

- the thickness of the bottom wall is between 0.3 and 2 millimeters;
- the border forms an angle of around 90 degrees with the back wall;
- the rear part is made of an alloy including aluminum;
- 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 support for receiving a motor vehicle, said fixing elements being positioned opposite the interrupted corners of the edge of the rear part.

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

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

The receiving support comprises means for fixing said storage battery module, said fixing means being intended to cooperate with the fixing elements of the side wall of the front part of said storage battery module.

The invention finally relates to a motor vehicle equipped with such an accumulator battery module assembly.

Of course, the various features, variants and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive.

Detailed description of the invention

The description which follows with reference to the attached drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be implemented.

On the attached drawings:

represents a schematic view of a motor vehicle equipped with a set of accumulator battery modules according to the invention; and

is an exploded view of the battery module assembly of the .

On the , a motor vehicle 1 is shown equipped with a set 10 of accumulator battery modules according to the invention.

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

As shown in FIGS. 1 and 2, the storage battery module assembly 10 comprises a storage battery module receiving support 20 (also referred to as “receiving support 20” hereinafter) and at least one storage battery module 30 (also referred to as “module 30” hereinafter).

The receiving support 20 is for example here secured to the motor vehicle 1, while the accumulator battery module 30 is attached to the receiving support 20.

There represents a schematic exploded perspective view of the elements comprised in the storage battery module 30. This module 30 comprises a rear portion 32, a front portion 34 and a plurality of storage battery cells 35 (for reasons of clarity, only one storage battery cell 35 is shown in the figure). ).

In this description, the terms "front" and "rear" are used in relation to the positioning of the element on the receiving support (on which the element concerned is attached). The rear of this element designates the side facing the receiving support on which the element is attached while the front designates the side facing away from this receiving support.

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

The rear portion 32 is made of a single piece. It is for example formed of an alloy comprising aluminum. Alternatively, it may be formed solely of aluminum.

As shown in the , the rear portion 32 comprises a bottom wall 32A and a border 32B running along the bottom wall 32A. The border 32B rises, towards the front, from the bottom wall 32A. This border 32B forms an angle of the order of 90 degrees with the bottom wall 32A. This 90-degree arrangement makes it possible to limit the size of the rear portion 32 (in particular when it is arranged in the receiving support 20).

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

The 32B border has a generally rectangular profile. Here, as can be seen on the , the edge 32B is interrupted at its corners. This truncated shape at the corners is advantageous for allowing the accumulator battery module 30 to be fixed to the receiving support 20.

Advantageously according to the invention, the bottom wall 32A has a thickness of less than 3 mm. This thickness of the bottom wall 32A then makes it possible to optimize the heat exchanges between the cells 35 of the storage battery (also called “cells 35” in this description) and the cooling circuit 27. Furthermore, such a thickness makes it possible to reduce the total mass of the storage battery module 30.

Preferably, the thickness of the bottom wall 32A is between 0.3 and 2 mm. More preferably, it is between 0.7 and 2 mm.

As shown in the , the front portion 34 of the storage 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 storage battery module 30. By way of illustration, as can be seen in the , the rear portion 32 and the front portion 34 form an inverted shoe box, with the rear portion 32 forming the lid of this box and the front portion 34 the container of this box.

The front part 34 is for example formed from aluminum. It has a greater rigidity than the rear part 32.

To compare the rigidity between the two parts (front and rear), a rigidity test can be implemented. 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 spaced 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. It is then considered that the front part 34 has a rigidity greater than that of the rear part 32 if, after the application of the mentioned stress, a greater deformation is observed at the rear part than at the front part 34.

As shown in the , 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.

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.

In order for these fixing elements 34C to be able to cooperate with the means 22C of the receiving support 20, the fixing 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 attached to 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.

The front part 34 and the rear part 32 are assembled so as to delimit a housing for receiving a plurality of accumulator battery cells 35 (only one of which is visible in the figure). ). In other words, when assembled, the front portion 34 and the rear portion 32 form a housing of the storage battery module 30 housing the plurality of storage battery cells 35.

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

In this description, the term "joining" means a method of assembling two metal walls placed end to end (in the extension of one another) so as to obtain a generally smooth final surface without any thickness offset between the two assembled 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 assembled by joisting to the corresponding part (i.e. located opposite the portion of the edge 32B) of the side wall 34B of the front part 34 ( ).

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

Furthermore, this method allows the assembly of a rear part and a front part with different thicknesses and formed from different materials while guaranteeing the rigidity and expansion properties essential to a battery module.

The rolling is here favored by the properties of the edge 32B as described previously. Indeed, a height of less than 10 mm and an orientation of the edge 32B at 90 degrees relative to the bottom wall 32A make it possible to improve the efficiency of the rolling.

Preferably here, the assembly by grooving 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.

Alternatively, the grooving can correspond to an assembly by brazing or even by mechanical fixing, making it possible to obtain a smooth final surface, without thickness offset between the edge of the rear part and the side wall of the front part.

The plurality of storage battery cells 35 are positioned in the housing formed by the assembly of the rear part 32 and the front part 34. The storage battery cells 35 are for example positioned next to each other. They are for example sixteen in number here.

In practice, each cell 35 of the accumulator battery is for example fixed by gluing, by a glue element 38 shown in the figure. , on the bottom wall 32A of the rear part 32 of the module 30.

The cells 35 are for example here cells with a flexible envelope, that is to say cells 35 whose envelopes can deform during their insertion into the housing formed by the front part 34 and the rear part 32 and during their charging and discharging. Advantageously, the front part 34 of the accumulator battery module 30 makes it possible to contain the deformation of the cells thanks to its properties described above.

More particularly, the soft-shell cells 35 comprise a soft outer shell which contains inside an electrolyte of organic solution or of a solution based on lithium carbonate and salts.

For example, this is a lithium-ion type electrolyte, wrapped in an envelope consisting 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.

These flexible-shell cells 35, well known to those skilled in the art, will not be described in more detail here.

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

As shown in the , the receiving support 20 here has a generally parallelepiped shape. It comprises a rectangular bottom 22, from the edges of which rise three side walls 23, 24, 25 which delimit between them a housing 21 for receiving the accumulator battery module 30. Here, the two side walls 23, 25 are located opposite one another while opposite the side wall 24, the receiving support 20 also has a side wall portion extending opposite this side wall 24 (but which is not shown in the for the sake of clarity).

The receiving support 22 comprises, at its bottom 22, a cooling circuit 27. The cooling effect is for example obtained from the circulation of water in the cooling circuit 27.

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

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 storage 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 storage battery module 30 so as to improve the efficiency of the thermal conduction between the cooling circuit 27 and the cells 35 (fixed on the bottom wall 32 of the rear part 32 of the storage battery module 30).

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.

The receiving support 20 is for example formed here so as to be sealed against drops of water or dust which could enter the accumulator battery module assembly 10. The sealing is here evaluated according to the IP67 standard according to the EN60529 standard.

In order to allow the module 30 to be fixed to the receiving support 20, the bottom 22 of the receiving support 20 comprises fixing means 22A. These fixing means 22A are designed to cooperate with the fixing elements 34C of the front part 34 of the side wall 34B of the module 30. There are as many fixing means 22A as there are fixing elements 34C on the side wall 34B of the front part 34 of the module 30.

Here, as shown in the , the fixing 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.

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.

The attachment of the storage battery module to the receiving support can be carried out differently. For example, according to a variant not shown, the border can be continuous over the entire periphery of the bottom wall (in other words, as a variant, the border can be continuous, including at its corners). In this case, the bottom wall of the rear part can have openings, for example located near the corners of the bottom wall of the rear part.

Thus, the fixing of the module 30 on the receiving support 20 can be carried out by passing fixing elements (such as screws) through the columns of the side wall of the front part, then through the openings of the bottom wall of the rear part so as to cooperate with complementary fixing means present in the bottom of the receiving support.

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

The embodiment described above only concerns a receiving support associated with a storage battery module.

The present invention is of course applicable in the case where a plurality of storage battery modules are included in the motor vehicle. In such a case, a plurality of sets 10 of storage battery modules juxtaposed next to each other in the motor vehicle may be considered. A single receiving support may also be considered accommodating a plurality of storage battery modules (the storage battery modules being positioned, for example, next to each other on the bottom of the single receiving support).

Finally, by making 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 forces generated by the battery cells in order to contain these expansion effects due to the cells themselves.

Thanks to the invention, it is therefore possible to implement a compromise in the production of the housing so as to obtain a certain rigidity while guaranteeing efficient cooling of the cells. Given the thickness characteristics of the rear part of the housing of the storage battery module, the heat exchanges between the cooling circuit and the cells are optimized, thus allowing efficient cooling of the storage battery module.

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

Claims (10)

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 with 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). The battery module (30) of claim 1, wherein the edge (32B) has a height of less than 10 millimeters. 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). Battery module (30) according to any one of claims 1 to 3, in which the thickness of the bottom wall (32A) is between 0.3 and 2 millimeters. Battery module (30) according to any one of claims 1 to 4, in which the front part (34) has a rigidity greater than that of the rear part (32). A battery module (30) according to any one of claims 1 to 5, wherein said border (32B) is interrupted at corners. Battery module (30) according to claim 6, in which the side wall (34B) of the front part (34) has, at its corners, fixing elements (34C) 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). Set (10) of accumulator battery modules comprising:
- a receiving support (20) for a battery module (30), said receiving support (20) being provided with a cooling circuit (27), and
- a storage battery module (30) according to any one of claims 1 to 7, the bottom wall (32A) of the rear part (32) of said storage battery module (30) being positioned in contact with said cooling circuit (27). Battery module assembly (10) according to claim 8 taken in the dependency of claim 7, in which the receiving support (20) comprises fixing means (22A) of said 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 battery module (30). Motor vehicle (1) comprising a battery module assembly (10) according to claim 8 or 9.