This application claims priority to German Patent Application No. DE 10-2022-134-726.5, filed Dec. 12, 2022, incorporated herein by reference.
The present invention relates to a cell carrier strut for receiving and separating several battery cells, a cell carrier composite system as well as a battery carrier and a battery housing for a high-voltage battery.
It is already known from prior art that in battery-powered electric vehicles, the battery cells of a high-voltage battery required for propulsion are usually accommodated in the area below the driver's cab. The structural design is usually chosen to be flat in order to keep the vehicle height as low as possible and the vehicle's center of gravity as low as possible. Due to the fact that the batteries to be received have a low mechanical load capacity, the aforementioned position outside the front and rear crash zone of the vehicle is the best possible position. However, this position on the underbody of the vehicle, combined with the low mechanical load capacity of the battery cells, in turn results in requirements for the safety of a battery carrier and a battery housing to receive and enclose the battery cells.
Due to the high density of the materials used in batteries, such as nickel, copper, etc., battery cells are generally very heavy, which in turn poses a challenge for the load capacity and dynamic loads on the necessary battery carriers and battery housings.
In order to increase the energy density of the battery cells at cell compound level, the cells are packed as tightly as possible without additional enclosures of individual battery cells that reduce the packing density. In prior art, this installation is often referred to as “Cell to Pack” (C2P). Compared to previous structures, in which the individual battery cells were initially combined in individual modules, which was referred to as “Cell to Module” (C2M), the use of the C2P structure can eventually significantly improve the vehicle range with the same installation space compared to the C2M structure.
The C2P structure generally requires a very rigid battery carrier and a very rigid battery housing, respectively, to be formed as the structural rigidity is not necessarily given by the cell compound or the individual battery cells.
For smaller cells, the individual parts forming the battery housing in particular must be sufficiently rigid and strong. Moreover, the cells require a battery cell carrier to receive the cells in the correct position, spaced apart and electrically insulated.
In prior art cell carriers, the cell carrier is particularly configured to receive round cells such that the individual cells are inserted axially into the openings in the cell carrier provided for this purpose. Very precise guidance of the battery cells is required during the assembly process. In the case of radially cooled cells, the cooling lines must also be threaded into this cell carrier between the battery cells. The cell carrier structures from prior art have so far been very complex to assemble. Furthermore, in prior art, the previous configurations of the cell carriers are primarily used for positioning the cells. The structural-mechanical properties, such as a load-bearing function, are fulfilled by the actual battery housing, wherein the battery cells are usually potted or bonded.
The problem with prismatic cells is that the cells deform or swell during the charging process, so that the resulting bulge on the cell carriers from prior art is disadvantageous, as the deformation causes the battery cells to shift relative to the cell carrier and/or the battery housing.
Due to the potting or bonding of the battery cells to the cell carrier, subsequent recycling will also be very difficult or even impossible. Furthermore, as described above, the assembly effort for mounting the cell carriers is very high in order to achieve the required rigidity and strength, respectively. In particular in the previous cell carrier structures, the battery housings or battery carriers are also required to ensure suitable crash safety for the battery cells.
Based on the aforementioned prior art, the object of the present invention is to provide an improved cell carrier and an improved cell carrier composite system which significantly reduces the assembly effort, simplifies subsequent recycling and furthermore increases the rigidity and crash safety of the cell arrangement without requiring the battery cells to be bonded or potted.
According to the invention, the aforementioned object is achieved by a cell carrier strut for receiving and separating several battery cells, a cell carrier composite system comprising several cell carrier struts, a battery carrier and a battery housing.
According to a first aspect, the present invention relates to a cell carrier strut for receiving and separating several battery cells comprising a carrier body extending along an extension direction from a first end to an opposite second end and a stacking direction orthogonal to the extension direction. The carrier body comprises a separating web for forming a separating section in the stacking direction, the separating web having a first and a second side surface opposite one another in the stacking direction. The first and/or the second side surface comprise, along the extension direction, several elevations adapted to the battery cells to be received for positioning and receiving the battery cells.
According to the invention, the term adaptation of the elevations is to be understood as such that the elevations are adapted to the shape and size of the battery cells to be received, so that at least a part of the first and/or second side surface comprising the correspondingly adapted elevations provides a contact surface or abutment surface for the battery cells to be received.
Due to the provided formation of elevations in the area of the first and/or the second side surface, corresponding indentations can of course as a consequence also be formed in the area of the first and/or the second side surface in accordance with the invention. In other words, the first and/or the second side surface can comprise both several elevations adapted to the battery cells to be received and/or also several indentations adapted to the battery cells to be received.
The separating web forms a cross-sectional plane orthogonal to the extension direction and forms an “I”-shaped cross-sectional profile of the carrier body, wherein the cross-sectional profile has a width dimension in the stacking direction and a height dimension orthogonal to the extension direction and orthogonal to the stacking direction, and wherein the height dimension is many times greater than the width dimension. The width dimension can vary along the extension direction due to the formation of the several indentations and/or elevations adapted to the battery cells to be received.
The several battery cells can be arranged at a distance from one another along the extension direction, at least in partial areas along the first and/or second side surface of the cell carrier strut. Here, the battery cells get into contact in partial areas with the respective side surfaces of the cell carrier, wherein elevations and/or indentations being formed on the side surface for at least partial receiving and spacing of the battery cells in the carrier body of the cell carrier strut.
According to the invention, it may be provided that the several battery cells arranged along a cell carrier strut are separated from one another by the elevations and indentations, respectively, of the cell carrier and are also sealed off from one another, respectively, so that the battery cells cannot come into contact with one another. The carrier body has elevations and/or indentations on the first and/or second side surface in order to receive the cells in a precise position, furthermore for electrical insulation of the individual cells and in order to advantageously transfer forces acting on the cells to the structure and to minimize or completely avoid force or load transfer to the actual battery cells.
In a further optional embodiment of the cell carrier strut, the different geometric configuration of the elevations and/or indentations allows the mixed installation or the alternating reception and arrangement of prismatic and cylindrical battery cells to receive the cells in the area of the carrier body of a cell carrier strut. The mixed installation can be achieved both within a row of stacks, i.e. along the extension direction of a cell carrier strut, and preferably in the stacking direction, but by means of geometric variations.
The stacking direction or a stacking direction is orthogonal to the extension direction of the cell carrier strut, along which stacking direction several cell carrier struts with battery cells received therebetween can be stacked or packed and joined together to form a cell carrier composite system. Here, the individual battery cells are received between a first side surface of a first cell carrier strut and a second side surface of a second cell carrier strut proportionally to form a cell carrier composite system. By providing the indentations and/or elevations on the two first and second side surfaces, any number of cell carrier struts with individual battery cells can be joined together in a modular fashion. The cell carrier strut according to the invention thus provides a modular system, wherein several cell carrier struts and individual battery cells can be joined together to form a compact cell carrier composite system.
According to the invention, it may be provided that the elevations in the areas of the first and/or the second side surface are formed to receive prismatic and/or cylindrical battery cells.
The carrier body can also comprise an upper transverse flange, which adjoins an upper end surface of the separating web to form an L-shaped or T-shaped cross-sectional profile of the carrier body and to form an upper contact surface for the battery cells to be received, which adjoins the respective first and/or second side surface.
Furthermore, it may be provided that the carrier body additionally comprises a lower transverse flange, which adjoins a lower end surface of the separating web to form a C-, Z- or double-T-shaped cross-sectional profile of the carrier body and to form a lower contact surface for the battery cells to be received, which is adjacent to the respective first and/or second side surface.
The lower and/or upper contact surface is substantially orthogonal to the respective first and second side surface, respectively. The lower and/or upper transverse flange can respectively adjoin or be attached centrally to the respective end surface of the separating web, so that the lower and/or upper web protrudes on both sides of the separating web in the area of the first and the second side surface and also forms an upper and/or lower contact surface to the two side surfaces. However, according to the invention, it may alternatively also be provided to attach the lower and/or upper transverse flange eccentrically to the respective end surface of the separating web or to connect it thereto, so that the lower and/or upper web also protrudes only on one side of the separating web in the area of the first or the second side surface and forms a lower and/or upper contact surface only to one of the two side surfaces. According to the invention, a T-profile or a double-T-profile can thus be formed in cross-section in case of a central arrangement of the lower or upper transverse flange, and exemplary L-, C- or Z-shaped profiles can be formed in case of an eccentric arrangement.
According to the invention, it may also be provided that the elements forming the carrier body and thus in particular the separating web and the at least one upper and/or lower transverse flange are manufactured proportionally and integrally, for example as a singular injection-molded part.
Furthermore, it may be provided that several spaced recesses or holes are formed in the upper and/or lower transverse flange along the extension direction for the passage of electrical contacts and/or of safety valves of the battery cells to be received, for example.
The carrier body can comprise a hybrid material structure comprising at least a first component formed from a plastic and a second component formed from a stiffening material to increase the mechanical properties.
The materials for increasing the mechanical properties can be introduced locally in the area of highest loads, so that these bear the main loads. However, according to the invention, the carrier body can also be formed from a single singular type of material.
A plurality of reinforcing fibers extending along the extension direction can be embedded in the carrier body. It may be provided that the reinforcing fibers are preferably embedded unidirectionally along the extension direction, for example as unidirectional or as several unidirectional fiber layers in the carrier body or are connected thereto in a load-bearing manner. However, according to the invention, it may also be provided that a fabric or laid scrim formed from reinforcing fibers is embedded in the carrier body or connected thereto in a load-bearing manner.
The reinforcing fibers can preferably be embedded in the upper and/or lower transverse flange and/or in the separating web.
The reinforcing fibers can be carbon fibers, glass fibers or metal wire, for example.
In a preferred embodiment, the carrier body can be formed proportionally from a thermoplastic short or long glass fiber-reinforced plastic and proportionally from a continuous fiber-reinforced thermoplastic.
Furthermore, it may be provided that the carrier body comprises at least one end element at the first and/or second end in the direction of the extension direction to form an end contact surface for the battery cells to be received, which end contact surface is adjacent to the respective first and/or second side surface.
In the area of the first and/or second end, the carrier body can comprise a fastening device for fastening the cell carrier strut or the carrier body to a battery carrier or to a battery housing.
Compressible padded elements can preferably be arranged in the area of the first and/or the second side surface. The compressible padded elements are also commonly referred to as compression pads or swelling pads, for example, wherein the compressible padded elements can preferably be made of foam or of an aerogel. The compressible padded elements can be arranged in the area of the first and/or the second side surface, in particular in the area of the elevations or indentations. The compressible padded elements can either be pre-fixed to the first and/or the second surface or installed or arranged in the cell carrier body together with the assembly of the prismatic cells.
At least one recess can be formed in the separating web to receive a preferably active temperature control element in the area of the carrier body. Furthermore, according to the inventio, it may be provided that at least one cooling element, such as a cooling channel, can be embedded or introduced directly during the manufacture of the cell carrier strut, for example using an injection molding process. The cooling element, in particular a cooling channel, can be overmolded with plastic and thus firmly and positively connected to the carrier body of the cell carrier strut. Integration in the injection molding process eliminates the process step in assembly. Similarly, if the cooling element is made of a metal profile, such as an aluminum profile, it would become part of the structure reinforcing the cell carrier strut. It may be provided to introduce the cooling elements in each of the carrier bodies of the cell carrier struts and thus provide cooling in the stacking direction at the front and rear side of each battery cell to be received.
Furthermore, according to the invention, it may be provided to form the cell carrier strut or the carrier body in multiple layers, at least from two parts, wherein the individual parts preferably consist of the same material and are connected or joined together, for example by a welding or other joining process.
By joining the individual parts, a cavity can be formed in the cell carrier strut or the carrier body. In general, the carrier body can comprise a cavity, which is introduced in the area between the first and the second side surface of the cell carrier body and forms a cavity in which, for example, cooling or temperature control medium can be transported. The walls defining the cavity are in turn at least partially adjacent to the battery cells to be received, so that the battery cells only have a small distance to the temperature control medium and can therefore be actively temperature-controlled in a particularly effective manner. The above-described embodiment has the advantage that the carrier body itself or the actual material of the carrier body is used directly for cooling and at the same time also forms a load-bearing structure for receiving the battery cells. A particular advantage of the aforementioned embodiment is the purity of the material used, so that the cell carrier strut according to the invention or the corresponding carrier body, which also comprises a temperature control device, can nevertheless be easily recycled.
According to the invention, it may be provided that the carrier body is configured for stacking or lining up several cell carrier struts along the stacking direction.
The carrier body can preferably comprise first and second latching or locking elements adapted to one another in the area of the lower and/or upper transverse flange for the load-bearing connection of the carrier body to at least one further cell carrier strut or at least one further carrier body of a further cell carrier strut.
The latching elements can be arranged such that the latching is performed in the assembly direction of the cells or the struts.
It may also be provided that the latching elements are arranged such that cylindrical battery cells can be installed in a meander-shaped manner with the same component by rotating a strut by 180°.
A carrier body comprising at least one upper transverse flange and/or one lower transverse flange can also comprise a one-piece continuous or multi-piece projection divided into sections on the side surface of at least one transverse flange facing away from the separating web for spacing the carrier body from a contact surface of a battery carrier or a battery housing.
According to the invention, it may be provided that the separating web is box-shaped in the cross-sectional plane to form an intermediate space between the first and the second side surface.
Furthermore, according to the invention, it may be provided to arrange a structural profile in the intermediate space, which structural profile is connected to the carrier body of the cell carrier strut in a load-bearing manner or is at least partially embedded and enclosed in the material of the carrier body.
At least one attachment point for the load-bearing connection of the carrier body to a battery carrier or a battery housing can be formed in the intermediate space. The attachment points can comprise threaded inserts for fastening screws that are screwed into the threaded inserts from the outside of the housing through the cover or bottom. The attachment points can include at least one molded bore in the carrier body so that a self-tapping screw can be used to fasten the carrier body to a battery carrier or to a battery carrier housing.
The attachment points can also comprise circumferential sealings for encapsulating the battery carrier or the battery housing when using a screw connection from the outside of the housing or the battery carrier.
According to a second aspect, the present invention relates to a cell carrier composite system comprising a plurality of cell carriers according to the first aspect of the invention for receiving and separating several battery cells and preferably at least one tensions strap.
For the configuration of the cell carrier system, the cell carriers can receive a plurality of individual battery cells and be connected to one another in the stacking direction, so that a plurality of individual battery cells are always received between a first and a second cell carrier strut. By providing a plurality of cell carrier struts arranged next to one another in the stacking direction and connected to one another, a cell carrier composite system is formed, wherein preferably the plurality of cell carrier struts are connected to one another in the stacking direction by means of at least one tension strap or are subjected to a tensile force in the stacking direction by the tension strap.
The at least one tension strap can be formed from a tension-resistant material and preferably comprise at least one layer of a unidirectional fiber tape, with the longitudinal direction of the fibers being aligned in the longitudinal direction of the tension strap.
According to a third aspect, the present invention relates to a battery carrier comprising a plurality of cell carrier struts according to the first aspect of the invention or at least one cell carrier composite system according to the second aspect of the present invention as well as a battery carrier frame and a battery carrier lower part. The battery carrier lower part is adapted to be connected to the battery carrier frame to form a receiving space open on one side for arranging the cell carrier composite system or the plurality of stacked cell carrier struts.
According to a fourth aspect, the present invention relates to a battery carrier housing comprising at least one battery carrier and also a battery housing upper part, wherein the battery carrier lower part and the battery housing upper part are adapted to be connected to batty carrier frame to form a receiving space enclosed on all sides for arranging the cell carrier composite system or the plurality of stacked cell carrier struts.
In the following, exemplary embodiments of the cell carrier strut, of an exemplary cell carrier composite system, a battery carrier and a battery housing are illustrated with reference to the accompanying Figures.
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Number | Date | Country | Kind |
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10 2022 134 726.5 | Dec 2022 | DE | national |