Battery module with tie rod element

Abstract

The invention relates to a battery module with a tie rod element (20), wherein the battery module (1) has a battery module housing, wherein the battery module housing has a base body, wherein the base body is designed as an extrusion profile, wherein the base body has an upper side wall (11) running along the extrusion direction of the extrusion profile and a lower side wall running along the extrusion direction, wherein the lower side wall is opposite the upper side wall (11) in a vertical direction (Z), wherein the upper side wall (11) and the lower side wall delimit an interior space (15) in the vertical direction (Z), wherein the battery module (1) has a battery cell stack, wherein the battery cell stack has at least two battery cells stacked in a stacking direction (X), wherein the tie rod element (20) is arranged between the at least two battery cells.

Description

[0001] The invention relates to a battery module with a tie rod element.

[0002] High-voltage batteries for motor vehicles, often also referred to as traction batteries, typically comprise one or more battery modules, with each battery module comprising several electrically interconnected battery cells. Due to the very high mechanical demands placed on battery module housings, extrusion profiles, particularly extruded profiles, are often used for battery module housings today, particularly in the outer areas of high-voltage motor vehicle batteries near the sills. It is entirely conceivable for the battery module housing to consist of an extrusion profile with open end faces to allow the battery cells to be inserted into the extrusion profile. Following insertion, the open end faces can be closed with head plates; these head plates are often forged components.

[0003] The demands on temperature control of high-voltage batteries in electric or partially electric vehicles are increasing rapidly due to increasing power density. The basic function of temperature control is to create an environment for the battery cells that guarantees optimal performance with a sufficient service life and a high level of safety. A particularly effective approach is so-called immersion cooling. In immersion cooling, a dielectric fluid, particularly a dielectric liquid such as cooling oil, directly surrounds the battery cells.

[0004] With very large battery cases and very high cooling fluid pressure, a very high force is exerted on the side walls of the battery module housing. This force can lead to severe deformation of the battery module housing, even to its failure. This effect is more pronounced on the side walls of the battery module housing with the largest surface area. With a rectangular extrusion cross-section, this therefore affects the wider side.

[0005] DE 10 2020 213 178 A1 discloses a battery device, wherein the battery device comprises one or more battery modules and a housing in which the one or more battery modules are accommodated or can be accommodated. The housing and the one or more battery modules each comprise a plurality of guide elements, wherein the one or more battery modules are inserted or can be inserted into the housing along an insertion direction by means of the guide elements. WO 2012 / 065 855 A1, DE 10 2018 214 528 A1, and DE 10 2018 128 977 A1 disclose further prior art.

[0006] DE 10 2020 119 285 A1 discloses a battery module having the features of the preamble of claim 1. CN 2 09 071 439 U, DE 10 2019 207 595 B3 and CN 1 16 885 378 A disclose further prior art.

[0007] The object of the present invention is to provide a battery module in which deformation of the housing due to internal pressure is avoided.

[0008] This object is achieved by a battery module having the features of claim 1. The dependent claims relate to advantageous developments.

[0009] The battery module according to the invention is a battery module for a high-voltage battery of an electrically or partially electrically powered motor vehicle. The battery module has a battery module housing, wherein the battery module housing has a base body, wherein the base body is designed as an extruded profile, wherein the base body has an upper side wall running along the extrusion direction of the extruded profile and a lower side wall running along the extrusion direction, wherein the lower side wall is opposite the upper side wall in a vertical direction, wherein the upper side wall and the lower side wall delimit an interior space in the vertical direction, wherein the battery module has a battery cell stack, wherein the battery cell stack has at least two battery cells stacked in a stacking direction, wherein a tie rod element is arranged between the at least two battery cells,wherein the battery cell stack has an upper side facing the upper side wall and a lower side facing the lower side wall, wherein the tie rod element has an upper end portion and a lower end portion opposite the upper end portion, wherein the upper end portion protrudes on the upper side of the battery cell stack relative to the battery cells and the lower end portion protrudes on the lower side of the battery cell stack relative to the battery cells, wherein the upper end portion has an upper anchoring structure extending along the extrusion direction and the lower end portion has a lower anchoring structure extending along the extrusion direction, wherein the upper side wall has an upper anchoring groove extending along the extrusion direction and open towards the interior space,wherein the lower side wall has a lower anchoring groove extending along the extrusion direction and open towards the interior, wherein the battery cell stack is inserted into the base body along the extrusion direction in such a way that the upper anchoring structure is inserted into the upper anchoring groove, preferably along the extrusion direction, and is thereby anchored in the vertical direction in the upper side wall, and the lower anchoring structure is inserted into the lower anchoring groove, preferably along the extrusion direction, and is thereby anchored in the vertical direction in the lower side wall.

[0010] The tie rod element is integrated into the battery cell stack and is thus pushed into the base body together with the battery cell stack when the battery cell stack is pushed into the interior of the base body. This eliminates the need for a separate assembly step for attaching a tie rod element to the base body. The design of the tie rod element, in particular the integration of the tie rod element into the battery cell stack, as well as the design of the anchoring groove in the upper side wall and the lower side wall, advantageously takes into account the manufacturing process of the base body, namely its production as an extruded profile, and the process of inserting the battery cell stack into the base body, namely its insertion along the extrusion direction of the extruded profile.The design of the anchoring structures and the anchoring grooves results in a positive connection of the tension rod element in the upper side wall or the lower side wall, such that when a force is applied to the upper side wall in a direction opposite to the lower side wall and / or when a force is applied to the lower side wall in a direction opposite to the upper side wall, for example due to an increasing internal pressure in the interior, the tension rod element is subjected to a tensile load and thus an unwanted expansion of the base body in the vertical direction or even a tearing of the base body in the area of ​​the upper side wall and the lower side wall is prevented.

[0011] Preferably, the battery cell stack is designed as a manageable unit, so that the battery cell stack can be inserted in its entirety into the base body.

[0012] It is considered particularly advantageous if the tie rod element is clamped between the battery cells.

[0013] The tie rod element is preferably designed as a thin-walled component. The tie rod element can be, for example, an extruded profile or a bent sheet metal component. A thin-walled design of the tie rod element has the advantage that the volumetric and gravimetric energy content of the battery cell stack does not decrease significantly, and the battery cell stack can be kept as small as possible in its stacking direction.

[0014] In particular, the battery module is a directly cooled battery module in which the battery cells are directly surrounded by a dielectric cooling fluid.

[0015] It is considered particularly advantageous if the tie rod element is arranged centrally in the battery cell stack. This is considered advantageous in terms of relieving the upper and lower side walls under tensile loads, and in particular, it prevents asymmetrical loading.

[0016] It is considered particularly advantageous if compression mats are arranged between the battery cells of the battery cell stack. Preferably, the tie rod element is arranged between two compression mats. This prevents damage to battery cells adjacent to the tie rod element, particularly in the event of a tensile load on the tie rod element.

[0017] It is considered particularly advantageous if the stacking direction is perpendicular to the vertical direction and perpendicular to the extrusion direction.

[0018] In a particularly preferred embodiment, it is provided that the upper anchoring structure and the upper anchoring groove form a tongue and groove connection and / or the lower anchoring structure and the lower anchoring groove form a tongue and groove connection.

[0019] In particular, the upper anchoring structure and / or the lower anchoring structure is T-shaped or L-shaped. In this context, it is considered particularly advantageous if the lower anchoring groove and / or the upper anchoring groove is also T-shaped or L-shaped.

[0020] It is considered particularly advantageous if the respective anchoring structure is accommodated in the respective anchoring groove with some play. This design simplifies the insertion of the respective anchoring structure into the respective anchoring groove when inserting the battery cell stack into the interior.

[0021] The battery module is intended to be an immersion-cooled battery module, with a dielectric cooling fluid flowing through the interior. The inventive design of the battery module has proven particularly advantageous for an immersion-cooled battery module, since, in an immersion-cooled battery module, the pressure prevailing in the interior leads to an outwardly directed compressive load on the upper side wall and the lower side wall of the base body.

[0022] In a particularly preferred embodiment, the base body has a rectangular cross-section.

[0023] Particularly in an immersion-cooled battery module, it has proven advantageous for the upper and lower side walls to form the largest side walls of the base body. Especially in an immersion-cooled battery module, the largest side walls of the base body are subjected to the greatest stress.

[0024] In an advantageous further development, it is provided that the tie rod element is designed as a surface component, in particular plate-shaped.

[0025] In particular, since the tie rod element is essentially subjected to tensile stress in the vertical direction, a thin-walled design of the tie rod element, in particular a plate-shaped design of the tie rod element, is to be regarded as advantageous with regard to the smallest possible expansion of the battery cell stack in the stacking direction, wherein due to the large surface area of ​​the tie rod element in a plane perpendicular to the stacking direction, the tie rod element nevertheless has a sufficiently high tensile load capacity.

[0026] In particular, the tie rod element is not designed to support the upper side wall and the lower side wall against each other with respect to compressive loading. Accordingly, it is considered particularly advantageous if the tie rod element is designed exclusively for tensile loading and not for compressive loading. This allows the tie rod element to be designed with a particularly thin wall thickness compared to a support element for supporting the upper side wall against the lower side wall, which must be designed for compressive loading and therefore requires a relatively thick wall.

[0027] It is considered particularly advantageous if the tie rod element has a longitudinal extension in the extrusion direction, with this longitudinal extension amounting to at least 90% of the longitudinal extension of the battery cells in the extrusion direction. Such a design has proven particularly advantageous with regard to absorbing the expected tensile forces.

[0028] In a particularly preferred embodiment, the base body is an extruded aluminum profile.

[0029] It is considered particularly advantageous if the material of the tie rod element is a metallic material, in particular aluminum.

[0030] In a particularly preferred embodiment, the material thickness of the tie rod element in the stacking direction is between 1 / 10 and 1 / 5 of the wall thickness of the upper side wall or the lower side wall. Such a material thickness has proven particularly advantageous in terms of sufficient tensile strength while still minimizing expansion in the stacking direction.

[0031] It is considered particularly advantageous if the material thickness of the tie rod element in the stacking direction is between 1.5 mm and 3.5 mm. This material thickness has proven sufficient to absorb the tensile forces.

[0032] In order to ensure the simplest and most cost-effective production possible, it has proven advantageous if the tie rod element is designed as a bent sheet metal component.

[0033] With regard to high stability and ease of production, it is considered advantageous if the tie rod element is constructed as a single piece. This single-piece design can be achieved, for example, by using an extruded profile for the tie rod element. However, it is considered particularly advantageous if the tie rod element is formed by bending a plate-shaped base body. In this context, it is considered particularly advantageous if the tie rod element is designed as a bent sheet metal component.

[0034] In a preferred embodiment, the upper anchoring structure and the lower anchoring structure are formed by forming. The upper anchoring structure and / or the lower anchoring structure can be formed by simply or repeatedly bending a plate-shaped base body.

[0035] It is considered particularly advantageous if the upper anchoring structure and / or the lower anchoring structure are formed, at least in part, by cold forming. Cold forming has the advantage that it allows for greater stability of the tie rod element in the cold forming area, particularly with regard to tensile loading.

[0036] It is considered particularly advantageous if the upper anchoring structure has overlapping bent sections and / or if the lower anchoring structure has overlapping bent sections. Preferably, the bent sections of the upper anchoring structure are cold-welded to one another in their overlapping region and / or the bent sections of the lower anchoring structure are cold-welded to one another in their overlapping region. Such a design can be manufactured particularly easily from a sheet metal component, whereby the cold welding of the overlapping bent sections allows a particularly stable anchoring structure to be achieved.

[0037] The terms "upper" and "lower," as well as analogous terms such as "top" and "bottom," serve only to distinguish between different structures and are not to be considered restrictive with regard to the orientation of these structures. For example, it is conceivable that the upper side wall of the battery module, when installed in the vehicle, faces forward in the vehicle's longitudinal direction. The same applies to directional specifications such as "vertical direction."

[0038] The following figures illustrate the invention in more detail using exemplary embodiments without being limited to them. They show: Fig. 1 a battery module according to a first embodiment in a schematic representation in a perspective view, Fig. 2 a part of the battery module according to Fig. 1 in an enlarged view, Fig. 3 a battery cell stack of the battery module according to Fig. 1 in a schematic representation, Fig. 4 a partial area of ​​a battery module according to a second embodiment in a view as in Fig. 2.

[0039] The Fig. 1 and Fig. 2 show a first embodiment of a battery module 1 according to the invention. The battery module 1 has a battery module housing, wherein the battery module housing has a base body, wherein the base body is designed as an extrusion profile. This extrusion profile has a rectangular cross-section. The base body has an upper side wall 11 running along an extrusion direction Y of the extrusion profile and a lower side wall 12 running along the extrusion direction Y. Furthermore, the extrusion profile has a left side wall 13 running along the extrusion direction Y and a right side wall 14 opposite the left side wall 13 in the X direction and running along the extrusion direction Y. The left and right side walls 13, 14 are each connected to the upper side wall 11 and the lower side wall 12.The upper side wall 11 and the lower side wall 12 delimit an interior space 15 of the battery module housing in the vertical direction Z. The left side wall 13 and the right side wall 14 delimit the interior space 15 in the X direction. The battery module 1 has a battery cell stack 2, wherein the battery cell stack 2 has a plurality of battery cells 30 stacked in a stacking direction, which in this case is identical to the X direction. A tension rod element 20, such as in particular the . Fig. 3. In the Fig. 1 and Fig. 2, the battery cells 30 have been omitted for reasons of clarity, although the tie rod element 20 is shown. The battery cell stack 2 has an upper side facing the upper side wall 11 and a lower side facing the lower side wall 12. The tie rod element 20 has an upper end section and a lower end section opposite the upper end section in the vertical direction Z. The upper end section protrudes on the upper side of the battery cell stack 2 in the vertical direction Z opposite the battery cells 30. The lower end section protrudes on the underside of the battery cell stack 2 in the vertical direction Z opposite the battery cells 30.

[0040] The upper end section has an upper anchoring structure 21 which runs along the extrusion direction Y and is here T-shaped. The lower end section also has a lower anchoring structure 22 which runs along the extrusion direction Y and is also T-shaped. The upper side wall 11 has an upper anchoring groove 16 which runs along the extrusion direction Y and is open in the direction of the interior space 15, which is complementary to the upper anchoring structure 21 and is thus also T-shaped. The lower side wall 12 has a lower anchoring groove which runs along the extrusion direction Y and is open in the direction of the interior space 15, which is complementary to the lower anchoring structure 22 and is thus also T-shaped.

[0041] The battery cell stack 2 is inserted into the base body via the open end faces of the base body along the extrusion direction Y, such that the upper anchoring structure 21 is inserted into the upper anchoring groove 16 along the extrusion direction Y and is thereby anchored in the upper side wall 11 in the vertical direction Z. The same applies to the lower anchoring structure 22 and the lower anchoring groove or the lower side wall 12. The open end faces can then be closed with head plates, whereby the head plates can be forged components.

[0042] The tie rod element 20 of the first embodiment is an extrusion profile.

[0043] The Fig. The second embodiment of the battery module 1 shown in Figure 4 differs from the first embodiment of the Fig.1 to 3 essentially by the design of the tie rod element 20. In the second embodiment, the tie rod element 20 is designed as a bent sheet metal component. Specifically, the upper end section of the tie rod element 20 is bent several times to form the first anchoring structure 21, wherein the upper anchoring structure 21 has overlapping bent sections 23, 24 that overlap in the vertical direction Z. These overlapping bent sections 23, 24 are cold-welded to one another in their overlapping region, so that the overlapping bent sections 23, 24 are connected to one another via a material-to-material connection 25 formed by the cold welding. List of reference symbols 1 battery module 2 battery cell stacks 11 upper side wall 12 lower side wall 13 left side wall 14 right side wall 15 Interior 16 upper connecting groove 20 tie rod element 21 upper anchoring structure 22 lower anchoring structure 22 bending sections 24 bending sections 25 Connection 30 battery cells X Stacking direction Y extrusion direction Z vertical direction

Claims

[1] Battery module (1) for a high-voltage battery of an electrically or partially electrically powered motor vehicle, wherein the battery module (1) has a battery module housing, wherein the battery module housing has a base body, wherein the base body is designed as an extrusion profile, wherein the base body has an upper side wall (11) running along the extrusion direction (Y) of the extrusion profile and a lower side wall (12) running along the extrusion direction (Y), wherein the lower side wall (12) is opposite the upper side wall (11) in a vertical direction (Z), wherein the upper side wall (11) and the lower side wall (12) delimit an interior space (15) in the vertical direction (Z), wherein the battery module (1) has a battery cell stack (2), wherein the battery cell stack (2) has at least two battery cells (30) stacked in a stacking direction (X),wherein a tie rod element (20) is arranged between the at least two battery cells (30), wherein the battery cell stack (2) has an upper side facing the upper side wall (11) and a lower side facing the lower side wall (12), wherein the tie rod element (20) has an upper end section and a lower end section opposite the upper end section in the vertical direction (Z), , characterized bythat the upper end section on the upper side of the battery cell stack (2) protrudes relative to the battery cells (30) and the lower end section on the underside of the battery cell stack (2) protrudes relative to the battery cells (30), wherein the upper end section has an upper anchoring structure (21) running along the extrusion direction (Y) and the lower end section has a lower anchoring structure (22) running along the extrusion direction (Y), wherein the upper side wall (11) has an upper anchoring groove (16) running along the extrusion direction (Y) and open in the direction of the interior space (15), wherein the lower side wall (12) has a lower anchoring groove running along the extrusion direction (Y) and open in the direction of the interior space (15), wherein the battery cell stack (2) is inserted into the base body along the extrusion direction (Y), such thatthat the upper anchoring structure (21) is inserted into the upper anchoring groove (16) and is thereby anchored in the vertical direction (Z) in the upper side wall (11) and the lower anchoring structure (22) is inserted into the lower anchoring groove and is thereby anchored in the vertical direction (Z) in the lower side wall (12), wherein the battery module (1) is an immersion-cooled battery module (1), wherein the interior space (15) is flowed through by a dielectric cooling liquid. [2] Battery module (1) according to claim 1, wherein the stacking direction (X) is perpendicular to the vertical direction (Z) and perpendicular to the extrusion direction (Y). [3] Battery module (1) according to one of claims 1 to 2, wherein the respective anchoring structure (21; 22) is received in the respective anchoring groove (16) with play. [4] Battery module (1) according to one of claims 1 to 3, wherein the battery cell stack (2) is designed as a manageable unit, so that the battery cell stack (2) can be inserted in its entirety into the base body. [5] Battery module (1) according to one of claims 1 to 4, wherein the upper side wall (11) and the lower side wall (12) form the largest side walls of the base body in terms of area. [6] Battery module (1) according to one of claims 1 to 5, wherein the tie rod element (20) has a longitudinal extension in the extrusion direction (Y), wherein the longitudinal extension is at least 90% of a longitudinal extension of the battery cells (30) in the extrusion direction (Y). [7] Battery module (1) according to one of claims 1 to 6, wherein a material thickness of the tie rod element (20) in the stacking direction (X) is between 1 / 10 and 1 / 5 of a wall thickness of the upper side wall (11) or the lower side wall (12). [8] Battery module (1) according to one of claims 1 to 7, wherein the tie rod element (20) is designed as a bent sheet metal component. [9] Battery module (1) according to one of claims 1 to 8, wherein the tie rod element (20) is integrated into the battery cell stack (2) such that when the battery cell stack (2) is pushed into the interior space (15) of the base body, the tie rod element (20) is pushed into the base body. [10] Battery module (1) according to one of claims 1 to 9, wherein the upper anchoring structure (21) has mutually overlapping bent sections (23, 24), wherein the bent sections (23, 24) are cold-welded to one another in their overlapping region and / or wherein the lower anchoring structure (22) has mutually overlapping bent sections (23, 24), wherein the bent sections (23, 24) are cold-welded to one another in their overlapping region.

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