Battery module for an electric vehicle

Abstract

A battery module (100) for an electric vehicle comprises an array of cells stacked in a first direction and several expandable elements interposed between them. The module also includes a housing (4) that contains the cell array. The housing (4) consists of a front cover (5) and a rear cover (6), such that each cover (5, 6) covers a corresponding end of the cell array in the first direction. The front cover (5) and the rear cover (6) are joined by side bands (7), arranged in a second direction perpendicular to the first, such that the front cover (5), the rear cover (6), and the side bands (7) form a perimeter housing that compresses the cell array.

Description

Battery module for an electric vehicle TECHNICAL SECTOR The present invention relates to battery modules for electric vehicles, and more specifically to modules comprising a housing that contains a set of cells. PRIOR STATE OF THE ART Electric vehicles are vehicles that are powered by one or more electric motors, which are powered by electric batteries, usually rechargeable. Historically, electric batteries have had high manufacturing costs, weight, long charging times, and limited lifespan and range, which has hindered the widespread adoption of battery electric vehicles. However, thanks to current technological advancements in batteries and environmental regulations, more and more manufacturers are opting for electric vehicles instead of traditional combustion engine vehicles. Electric batteries consist of multiple electrochemical cells that convert stored chemical energy into electrical current. The cells are stacked in modules, and vehicles may comprise one or more interconnected modules. The modules typically include an outer casing that houses the multiple cells. The outer casing usually has covers that are welded together to form the housing. However, there are also casings where the covers are secured by clips, meaning without welding or additional fasteners. In this regard, EP3190642 A1 describes a battery module for an electric vehicle comprising a cell assembly consisting of a plurality of cells stacked in a first direction, and a plurality of expandable elements interposed between the battery cells. The module also comprises a housing that contains the cell assembly. The housing comprises six caps that are joined and secured together by clips along their edges, each cap covering one end of the rectangular prism that forms the cell assembly. EP3629396A1 further describes a battery module comprising a plurality of cells housed in a module housing comprising a bottom plate, which forms the base of the battery module, and two side plates extending from the bottom plate. Both side plates are inclined so as to act as compression plates.The battery module also comprises a second module housing that acts as a top cover. US2014087231A1 further describes a battery module comprising a plurality of cells housed in a casing formed by a retaining band having a front band, a rear band, and side bands, defining a perimeter housing. The plurality of cells is sandwiched between a front and a rear compression plate, said compression plates being arranged within the perimeter housing of the casing together with the plurality of cells. The battery module further comprises a top cover and a bottom cover. EXPLANATION OF THE INVENTION The object of the invention is to provide a battery module for an electric vehicle, as defined in the claims. The battery module of the invention comprises a cell assembly consisting of a plurality of battery cells stacked in a first direction, and a plurality of expandable elements interposed between the battery cells. The module also comprises two lateral compression plates covering a corresponding end of the cell assembly in a second direction perpendicular to the first direction, and a housing enclosing the cell assembly. The cell assembly is sandwiched between the compression plates. The housing comprises a front cover and a rear cover, each covering a corresponding end of the cell assembly along the first direction.The front and rear covers are joined by side bands, these side bands being arranged in the second direction, such that the front cover, rear cover, and side bands form a perimeter housing in which the cell assembly is compressed. The compression plates are arranged inside the perimeter housing of the casing along with the cell assembly. The casing also comprises a top cover and a bottom cover, the top and bottom covers being fixed to the compression plates. The connection between the top cover and the compression plates, and between the bottom cover and the compression plates, is by clipping, the compression plates comprising a plurality of recesses, and the top and bottom covers comprising a plurality of tabs, the tabs of the top and bottom covers being retained in a respective recess of the compression plates. The battery module of the invention facilitates assembly because the perimeter housing is configured to retain the cell assembly, preventing the cells and expandable elements from collapsing. Likewise, if one of the cells in the cell assembly needs to be replaced or repaired, the cells do not crumble when the interior of the housing is accessed, as the cell assembly is contained and retained within the perimeter housing. These and other advantages and features of the invention will become evident from the figures and the detailed description of the invention. DESCRIPTION OF THE DRAWINGS Figure 1 shows a perspective view of an embodiment of the battery module according to the invention. Figure 2 shows an exploded view of the battery module from Figure 1. Figure 3 shows the perimeter housing of the battery module of Figure 1, which is formed by the front cover, the rear cover, and the side bands. Figure 4A shows the cell assembly and compression plates housed in the perimeter housing of the battery module in Figure 1, with the bottom cover mounted and the top cover unmounted. Figure 4B shows the cell assembly and compression plates housed in the perimeter housing of the battery module, with the lower cover mounted and the upper cover, according to another embodiment of the invention, not mounted. Figure 5 shows a sectional view of the battery module of Figure 1 but without the cell assembly. Figure 6 shows a detail of the sectioned view of Figure 5. Figure 7 shows a detail of the joint between the bottom cover and the front cover of the battery module of Figure 1. Figure 8 shows a detail of the joint between the top cover and the front cover of the battery module of Figure 1. DETAILED EXPLANATION OF THE INVENTION Figure 1 shows an embodiment of the battery module according to the invention. The battery module 100 of the invention is suitable for use in an electric vehicle, such as a passenger car, van, truck, or even a bus, to power said vehicle. The electric vehicle battery will consist of a plurality of modules 100 that can be electrically connected in series and / or in parallel. Module 100 of the invention comprises a cell assembly 1 comprising a plurality of battery cells 2 stacked along a first direction X, and a plurality of expandable elements 3 interposed between the battery cells 2, as shown in Figure 2. Module 100 also comprises a housing 4 that houses the cell assembly 1. The battery cells 2 are preferably of the pouch or sleeve type, commonly When the module 100 of the invention is in use, the cells 2 tend to increase their thickness in the first X direction due to expansion, and the expandable elements 3 tend to reduce their thickness in the same proportion in the first X direction, so that the expandable elements 3 compensate for the deformation suffered by the cells 2. The housing 4 comprises a front cover 5 and a rear cover 6 such that each cover 5 and 6 covers a corresponding end of the cell assembly 1 along the first direction X. The front cover 5 and the rear cover 6 are joined by side bands 7, said side bands 7 being arranged along a second direction Y perpendicular to the first direction X, such that the front cover 5, the rear cover 6 and the side bands 7 form a perimeter housing 8 in which the cell assembly 1 is compressed. The side bands 7 hold the front cover 5 and the rear cover 6 together, also creating the perimeter housing 8. This perimeter housing 8 facilitates the assembly of the battery module 100, as the cell assembly 1 is retained within it, preventing the cells 2 and the expandable elements 3 from falling apart during the construction of the battery module 100. Similarly, if one of the cells 2 in the cell assembly 1 needs to be replaced or repaired, the cells 2 do not fall apart when the interior of the housing 4 is accessed, as the cell assembly 1 is contained and retained within the perimeter housing 8, both in the first X direction and the second Y direction. In the preferred embodiment of the invention, the front cover 5, the rear cover 6, and the side bands 7 are formed from a single piece, preferably made of plastic, and more preferably of glass fiber-based polyamide. Furthermore, this plastic has several properties, such as being lightweight and fire-resistant.The front cover 5 and the rear cover 6 are rigid due to their thickness; however, the side bands, due to their slender configuration, i.e., due to the relationship between length and thickness, are configured to, on the one hand, allow a small flex when a certain force is exceeded along the first X direction, which facilitates the insertion of the cell assembly 1 during the assembly of the module 100 of the invention, and on the other hand, the side bands 7 resist the deformation suffered by the cells 2 in use, so the side bands 7, together with the expandable elements 3, contribute to maintaining the dimensions of the cell assembly 1 when the module 100 is in use. During the assembly of module 100 of the invention, the cell assembly 1 is externally compressed along the first direction X to insert said cell assembly 1 into the peripheral housing 8, such that the expandable elements 3 are compressed, passing into a compressed state. When the external force ceases, the expandable elements 3 tend to return to their original position, passing into an extended state, so that thanks to the expandable elements 3, the cell assembly 1 remains attached to the side bands 7 of the peripheral housing 8, the side bands 7 being configured to maintain the dimensions of the cell assembly 1, whether module 100 is in use or not. As already mentioned, during the use of module 100, the expandable elements 3 absorb the deformation of the cells 2 in the first X direction, going into a compressed state. Then, when module 100 is not in use and the cells 2 tend to recover their original thickness, the expandable elements 3 expand, going into an extended state, ensuring that the set of cells 1 remains attached to the side bands 7. These side bands 7 are configured to resist both the expansion force of the expandable elements 3 and the expansion or dilation of the cells 2 in the first X direction. In the preferred embodiment of the invention, the battery module 100 also comprises two lateral compression plates 9 covering a corresponding end of the cell assembly 1 along the second Y direction, such that the cell assembly 1 is sandwiched between the compression plates 9, as shown in Figure 2. The compression plates 9 are arranged inside the perimeter housing 8 of the casing 4 together with the cell assembly 1, as shown in Figures 4A or 4B. In the preferred embodiment of the invention, the housing 4 also comprises an upper cover 10 and a lower cover 11, the upper cover 10 and the lower cover 11 being fixed to the compression plates 9, as will be detailed later. The compression plates 9 are therefore removably joined together via the top cover 10 and the bottom cover 11, the compression plates 9 also being configured to maintain the dimensions of the cell assembly 1. In this way, the cell assembly 1 is held in place by the compression plates 9 and by the side bands 7, as detailed below. The compression plates 9, which are preferably made of plastic, are configured to withstand both the expansion force of the expandable elements 3 in the first X direction, as well as the expansion or dilation of the cells 2. The side bands 7, therefore, besides facilitating the assembly of module 100, also reinforce the function of the compression plates 9, for example, by preventing the compression plates 9 from bulging or by preventing them from being oversized. Thus, the compression plates 9 and the side bands 7 contribute to maintaining the dimensions of the cell assembly 1, together with the expandable elements 3, in a more reliable and secure manner. In the preferred embodiment of the invention, the connection between the upper cover 10 and the compression plates 9, and the lower cover 11 and the compression plates 9, is by clipping, as detailed below. In the context of the invention, the clipping connection refers to a type of quick connection where the elements forming the housing 4 of the battery module 100 of the invention are joined together in a simple and quick manner, without the need for additional fastening means, such as screws or rivets, or welded joints. In the preferred embodiment of the invention, each compression plate 9 comprises a plurality of housings 12, as shown, for example, in Figure 2, and the upper 10 and lower 11 covers comprise a plurality of tabs 13, as shown in detail in Figure 6, the tabs 13 of the upper cover 10 and lower cover 11 being retained in a respective housing 12 of the compression plates 9, as shown in Figure 6. Half of the housings 12 of each compression plate 9 are arranged in the upper part, i.e., near the upper cover 10, and the other half in the lower part, i.e., near the lower cover 11, as shown in Figure 2. The peripheral edges of the upper cover 10 are folded towards the lower cover 11, so that the cross-section of the upper cover 10 comprises an inverted U-shaped silhouette. The tabs 13 of the upper cover 10 that cooperate with the compression plates 9 are arranged inside the respective folded peripheral edge, with the tabs 13 protruding from the inner surface of the peripheral edge, as shown in Figures 5 or 6. In the preferred embodiment of the invention, the top cover 10 is made of plastic and the tabs 13 are obtained during the manufacturing process of the top cover 10, i.e., by molding. The peripheral edges of the lower cover 11 are folded towards the upper cover 10, so that the cross-section of the lower cover 10 comprises a U-shaped silhouette. The tabs 13 of the lower cover 13, which cooperate with the compression plates 9, are arranged on the opposing peripheral edges that cooperate with the compression plates 9, as shown, for example, in Figures 2 or 5, and also project into the module 100. In the non-limiting example shown in the figures, the lower cover 11 is metallic, preferably aluminum, and the tabs 13 of the lower cover 13 are formed by stamping, i.e., by folding part of the peripheral edge into the module 100 to create the corresponding tab 13, as shown, for example, in the detail of Figure 6. The material of the lower cover 11 facilitates heat dissipation when the module 100 is in use.The lower cover 11, when module 100 is mounted in the vehicle, works in conjunction with a cooling system (not shown in the figures) to ensure that cells 2 of cell assembly 1 are maintained within their optimal operating temperature range. In cold environments, cells 2 may need to be heated to operate within their temperature range. This could be achieved either by the same cooling system operating in reverse or by an additional heating system (not shown in the drawings) that works in conjunction with the lower cover 11. with a cooling system, not shown in the figures. In this case, the tabs 13 that cooperate with the compression plates 9 can be obtained by stamping, as in the lower cover 11, but otherwise this cover 13 can be obtained in one way or another. In another variant of the invention, not shown in the drawings, the compression plates 9 could comprise tabs instead of housings, and the lower and upper caps housings instead of tabs, without altering the concept of the invention. The top cover of the invention, according to any of the described embodiments, and the bottom cover 11 can also be attached to the front cover 5 and rear cover 6, this attachment preferably being made by clipping, as detailed below. The lower cover 11 comprises a plurality of housings 14, arranged on the folded peripheral edge, and the front cover 5 and rear cover 6 comprise a plurality of tabs 15 that protrude into the module 100, the tabs 15 of the front cover 5 and rear cover 6 being retained in a respective housing 14 of the lower cover 11, as shown in the detail of Figure 7 where the fixing between the lower cover 11 and the front cover 5 is shown. In the preferred embodiment of the invention the front cover 5 and rear cover 6 are made of plastic, therefore the tabs 15 are obtained by molding, although other ways of obtaining the tabs 15 are not ruled out. In the preferred embodiment of the invention, the top cover 10 comprises a plurality of arms 16, as shown in Figure 4A. These arms 16 are arranged on the opposing peripheral edges that cooperate with the front cover 5 and rear cover 6, and are oriented towards the front cover 5 and rear cover 6. Each arm 16 comprises a housing 16a, and the front cover 5 and rear cover 6 comprise a plurality of tabs 17, the tabs 17 of the front cover 5 and rear cover 6 being retained in a respective housing 16a of the arms 16 of the top cover 10, as shown in the detail of Figure 8, which shows the connection between the top cover 10 and the front cover 5. In another variant of the invention, not shown in the drawings, the arms 16 of the top cover 10 could comprise tabs instead of housings, and the front cover 5 and top cover 6 housings instead of tabs, without altering the concept of the invention. plurality of housings 14, arranged on the folded peripheral edge, and the front 5 and rear 6 covers comprise a plurality of tabs projecting into the module 100, not shown in the figures, retaining The implementation of figure 4B could include tabs instead of housings and the front cover 5 and rear cover 6 could include 5 and rear 6, without altering the concept of the invention. As shown in Figure 1, the front cover 5, part of the top cover 10 (i.e., part of the folded peripheral edge of the top cover 10), and part of the bottom cover 11 (i.e., part of the folded peripheral edge of the bottom cover 11) form the front cover of the housing 4 along the first X direction. The rear cover 6, part of the top cover 10 (i.e., part of the folded peripheral edge of the top cover 10), and part of the bottom cover 11 (i.e., part of the folded peripheral edge of the bottom cover 11) form the rear cover of the housing 4 along the first X direction. Part of the top cover 10 (the unfolded portion) forms the top cover of the housing 4, and part of the bottom cover 11 (the unfolded portion) forms the bottom cover of the housing 4.Likewise, the side bands 7, part of the top cover 10 (i.e., part of the folded peripheral edge of the top cover 10), and part of the bottom cover 11 (i.e., part of the folded peripheral edge of the bottom cover 11) form the side covers of the housing 4 along the second Y direction. In this way, a housing 4 is achieved that is easy to assemble and protects the cells 2 from the environment. In the preferred embodiment of the invention, a thermal element 18 of the module 100 of the invention, with high thermal conductivity, is arranged between the lower cover 11 and the cell assembly 1, as shown in Figure 2. This thermal element 18 helps to dissipate the heat generated by the cell assembly 1. This thermal element 18 is a sheet thermal paste that covers the end of the cell assembly 1 along the first X direction and has high thermal conductivity, so that it directs the heat accumulated in the module 100 of the invention towards the lower cover 11 for dissipation. In the preferred embodiment of the invention, where the top cover 10 is made of plastic, at least one expandable element 19 is arranged between the top cover 10 and the cell assembly 1 to ensure contact between the upper end of the cell assembly 1 and the top cover 10. In cell set 1, instead of an expandable element, another thermal element 18 of high thermal conductivity is provided to direct As shown in Figure 2, the module 100 of the invention also comprises at least one connection element 21 that enables electrical connection between the cells 2 of the cell assembly 1. The preferred embodiment of the invention comprises two connection elements 21, one connection element 21 being arranged between the cell assembly 1 and the front cover 5 and the other between the cell assembly 1 and the rear cover 6. On the other hand, module 100 of the invention also comprises a connector 20 to allow electrical connection of module 100 with other vehicle modules and / or with the vehicle's battery connectors and contactors. In the preferred embodiment of the invention, the connector 20 is arranged between the expandable element 19 and the top cover 10. To facilitate the assembly of module 100 of the invention, the lower cover 11 could be attached in a preliminary stage to the front cover 5 and rear cover 6, and then the cell assembly 1 with the compression plates 9 would be placed inside the perimeter housing 8, and finally, after placing all the components of module 100, the cell assembly 1 and the compression plates 9 would be placed inside the perimeter housing 8.

Claims

1. Battery module for an electric vehicle, comprising - a cell assembly (1) comprising a plurality of battery cells (2) stacked along a first direction (X), and a plurality of expandable elements (3) interposed between the battery cells (2), - two lateral compression plates (9) covering a corresponding end of the cell assembly (1) along a second direction (Y) perpendicular to the first direction (X), the cell assembly (1) being sandwiched between the compression plates (9), and - a housing (4) enclosing the cell assembly (1), the housing (4) comprising a front cover (5) and a rear cover (6), each cover (5, 6) covering a corresponding end of the cell assembly (1) along the first direction (X), the front cover (5) and the rear cover (6) being joined by side bands (7), said side bands being (7) arranged according to the second direction (Y),so that the front cover (5), the rear cover (6), and the side bands (7) form a peripheral housing (8) in which the cell assembly (1) is compressed, the compression plates (9) being arranged inside the peripheral housing (8) of the casing (4), characterized in that the compression (9) is by clipping, the compression plates (9) comprising a plurality of housings, and the bottom cover (11) a plurality of tabs (13), the tabs being retained by the compression (9).

2. Battery module according to claim 1, wherein the front cover (5), the rear cover (6), and the side bands (7) are formed from a single piece, preferably of plastic and more preferably of polyamide.

3. are fixed to the front cover (5) and rear cover (6).

4. and rear cover (5, 6), and the bottom cover (11) and the front and rear covers (5, 6) are by clipping.

5. Battery module according to claim 4,wherein the lower cover (11) comprises a plurality of housings (14), and the front cover (5) and the rear cover (6) comprise a plurality of tabs (15), the tabs (15) of the front cover (5) and the rear cover (6) being retained in a respective housing (14) of the lower cover (11).

6. Battery module according to claim 3 or 4, wherein the upper cover (10) comprises a plurality of arms (16), each arm (16) comprising a housing (16a), and the front cover (5) and the rear cover (6) comprise a plurality of tabs (17), the tabs (17) of the front cover (5) and rear cover (6) being retained in a respective housing (16a) of the arms (16) of the upper cover (10).

7. Battery module according to any of claims 1 to 6, wherein the front cover (5), part of the top cover (10) and part of the bottom cover (11) form the front cover of the housing (4) along the first direction (X), the rear cover (6),Part of the top cover (10) and part of the bottom cover (11) form the rear cover of the housing (4) along the first direction (X), part of the top cover (10) forms the top cover of the housing (4), and part of the bottom cover (11) forms the bottom cover of the housing (4).

8. Battery module according to any of claims 1 to 7, wherein the side bands (7), part of the top cover (10), and part of the bottom cover (11) form the side covers of the housing (4) along the second direction (Y).

9. Battery module according to any of claims 1 to 8, wherein the bottom cover (11) is made of metal, preferably aluminum.

10. Thermal element that helps dissipate the heat generated by the cell assembly (1).

11. Battery module according to any of claims 1 to 9, wherein the top cover (10) is made of plastic, and at least one expandable element (19) is disposed between the top cover (10) and the cell assembly (1).

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