DE102021120133A1 - Housing element, energy storage housing and method for producing a housing element - Google Patents

Abstract

Housing element for an energy storage housing, comprising an arrangement area which is designed for arranging a multiplicity of energy storage cells, the housing element being double-walled in the arrangement area, comprising an outer wall and an inner wall, the outer wall being formed from a composite material, and the inner wall being surrounded by a on the outer wall arranged reinforcement member is formed.

Description

The present invention relates to a housing element for energy storage housings, an energy storage housing and a method for producing a housing element.

In order to meet the required ranges, partially and fully electrically operated motor vehicles have large energy storage devices, which require correspondingly large energy storage device housings. In passenger cars, such energy storage housings often take up a large area of the underbody of the respective vehicle. The manufacture of such housings brings with it a number of challenges. The weight is particularly problematic in this context. Due to the size of the components, there are also certain limitations with regard to the available manufacturing processes. For example, it is not easily possible in terms of system technology to produce die-cast components of any size. Due to the often exposed installation situation, cf. the aforementioned underbody, the requirements with regard to crash behavior or other mechanical effects as well as corrosion protection are also important issues. Even in the case of a thermal event within the energy store itself, high demands are placed on such housings.

It is therefore an object of the present invention to specify a housing element for an energy storage housing, an energy storage housing and a method for producing a housing element, wherein the aforementioned disadvantages are to be eliminated and in particular a housing element is to be specified which can be produced inexpensively with optimal mechanical properties.

This object is achieved by a housing element according to claim 1, by an energy storage housing according to claim 11 and by a method according to claim 12. Further advantages and features emerge from the subclaims and the description and the attached figures.

According to the invention, a housing element for an energy storage housing comprises an arrangement area which is designed for arranging a large number of energy storage cells, the housing element being double-walled in the arrangement area at least in areas, preferably over the entire surface, comprising an outer wall and an inner wall, the outer wall being formed from a composite material , and wherein the inner wall is formed by a reinforcement element arranged on the outer wall. The use of a composite material for the outer wall expediently brings with it the advantage that a separate treatment for corrosion protection, such as the application of a coating provided for this purpose, can be dispensed with. In addition, composite materials are advantageously light and, depending on their structure and composition, can absorb high mechanical loads. The reinforcement element can be explicitly designed to reinforce the outer wall in the arrangement area, which means, on the one hand, reinforcement against mechanical effects from “outside” as well as from “inside” in the event of a thermal event in the energy store. This can lead to an explosive increase in pressure in the energy store, which places high demands on the thermal/mechanical resilience of the energy store housing and its components. In the present case, these can advantageously be met in a targeted manner via the reinforcement element, while the housing element as such is formed from the composite material.

According to a particularly preferred embodiment, the reinforcement element is a steel sheet. The use of steel as a material is advantageous because this material is relatively inexpensive and functionally offers many advantages, e.g. B. with crash loads. The high tensile strength and high toughness of steel materials are particularly noteworthy in this context. Advantageously, the steel layer or steel ply enables very good thermal protection in the event of a thermal event, as just described. In the event of a short circuit within a high-voltage battery, temperatures of up to 1000°C and more can occur. The sheet steel advantageously enables targeted and permanent reinforcement of the housing element. EMC requirements (EMC - electromagnetic compatibility) can also be well met when using sheet steel.

According to one embodiment, a high-strength steel is used as the steel material. For example, the thin wall thicknesses mentioned below, down to 0.3 mm, are made possible with this.

According to one embodiment, the reinforcing element is provided with an anti-corrosion layer on one or both sides. The sheet steel is, for example, KTL or PVC-coated (KTL - cathodic dip coating, PVC - polyvinyl chloride).

According to one embodiment, the reinforcing element is coated as an individual part, in particular KTL-coated (individual part KTL). Alternatively, the reinforcing element consists of a single or Strip material coated on both sides, in particular organically, is obtained or produced. (Organic) strip coating or coil coating methods allow a simplification of the process, since the reinforcing element can be produced quickly and efficiently by cutting the strip material to length.

The aforementioned coating is preferably formed in particular on that side of the reinforcement element which is oriented towards the arrangement of the energy storage cells. This enables the direct or indirect arrangement of the energy storage cells, for example by means of gluing.

According to one embodiment, the energy storage cells are lithium-ion cells. The energy storage cells preferably have solid housings, for example prismatic housings, particularly preferably cylindrical housings. Round cells, for example, are preferred energy storage cells.

According to a preferred embodiment, the reinforcement element, ie in particular the sheet steel, is of flat or even or planar design. This configuration has the advantage that little installation space is wasted. In addition, depending on the installation position of the housing element, the center of gravity of the motor vehicle can be lowered. The expression “flat” or “even” or “planar” is not to be understood to mean that the reinforcement element/steel sheet cannot have any beads or edges for targeted mechanical reinforcement. However, the reinforcement element or sheet steel preferably has no profile, chamber structure, hollow structure or the like.

What has been said applies analogously and correspondingly to the outer wall in the arrangement area, which is also preferably designed to be flat or planar in the aforementioned sense.

According to a preferred embodiment, a wall thickness ratio of the inner wall to the outer wall in the arrangement area is 0.08 to 0.9, in particular 0.1 to 0.6 or also 0.2 to 0.5. Tests have shown that an optimum power-to-weight ratio can be achieved within the range of the aforementioned ratios. This means that a housing element whose production takes into account the above-mentioned conditions can withstand the highest mechanical loads while being light in weight.

According to one embodiment, the reinforcement element/steel sheet has a wall thickness of 0.3 to 1.2 mm. According to one embodiment, the outer wall has a wall thickness of 1.5 to 3.5 mm in the arrangement area. An adhesive layer formed therebetween, if any, has a thickness of preferably 0.3 to 0.7 mm.

According to one embodiment, the reinforcing element, in particular the sheet steel, has a wall thickness of preferably 0.3 to 1.2 mm, particularly preferably about 1 mm. In the arrangement area, the outer wall preferably has a wall thickness in a range from 1.5 to 2.5 mm, particularly preferably in a range from 1.7 to 2.3, very particularly preferably about 2 mm.

According to one embodiment, the reinforcing element has a thickness of 0.3 to 0.9 mm, particularly preferably 0.7 mm. In the arrangement area, the outer wall has a wall thickness of preferably 1.5 to 2.5 mm, particularly preferably in a range of 1.7 to 2.3 mm, very particularly preferably 2 mm.

According to one embodiment, the reinforcing element/steel sheet has a wall thickness of 0.3 to 0.9 mm, particularly preferably 0.7 mm. According to one embodiment, the outer wall in the arrangement area has a wall thickness of 2.5 to 3.5 mm, particularly preferably 2.7 to 3.3 mm, very particularly preferably 3 mm.

According to one embodiment, the reinforcement element is attached at least in sections to the outer wall in a form-fitting and/or force-fitting and/or material-locking manner. The fastening can be designed over a large area or also in certain areas, for example in a punctiform manner.

According to one embodiment, the outer wall and the inner wall are attached to one another in areas or over the entire surface by means of adhesive.

The reinforcement element is expediently fastened to the outer wall in a rotationally and/or shear-proof manner.

The reinforcement element, in particular the sheet steel, is preferably formed or attached during the manufacture of the outer wall, or more generally of the housing element. The reinforcement element is preferably embedded in the housing element at least in regions. This is made possible by the fact that the reinforcement element is already inserted into the tool, by means of which the housing element is formed.

The side of the reinforcement element oriented towards the outer wall is preferably provided with an adhesive structure which optimizes the connection to the outer wall. According to one embodiment, the reinforcement element is primed or roughened to optimize or ensure adhesion.

According to one embodiment, the adhesive structure is provided via an adhesion promoter. The reinforcing element is expediently coated with an adhesion promoter, such as a hot-melt adhesive.

According to a preferred embodiment, the composite material is a short- and/or long-fiber-reinforced plastic, in particular a long-fiber-reinforced thermoplastic (LFT) or a thermoplastic molding compound. Preferred reinforcing fibers are: glass fibers, carbon fibers, aramid fibers, although this list is not to be understood as exhaustive. The fibers are referred to as "long" if they are at least several millimeters in length. Compared to fiber-reinforced duromers, for example, LFT have the advantage that they are tougher.

Preferred manufacturing processes are injection molding processes and pressing processes. According to a preferred embodiment, the housing element is produced by means of LFT extrusion. The reinforcement element is preferably placed in the cavity of the tool, where it is fixed, for example, using suitable positioning/holding elements, such as pins, and/or magnetically.

According to one embodiment, the composite material is a fiber-reinforced duromer. These are advantageously distinguished, for example, by a high compressive strength.

The housing element is preferably designed in the form of a trough. The necessary volume of the arrangement area, which is necessary for the arrangement of the largest possible number of energy storage cells, is advantageously produced via the trough shape. In the present case, preference is given to using prismatic cells, particularly preferably round cells, which, according to one embodiment, are arranged in particular in an upright position in the arrangement area.

The housing element, which is preferably trough-shaped, preferably comprises a central part and two end parts, each formed on the end face. The central part and the end parts expediently form side walls that run around the arrangement area and extend away from it, cf. the aforementioned trough shape. Further functions can expediently be integrated into the front part or parts, such as attachment points for vehicle structural components, chassis parts, etc.

Expediently, the housing element has a peripheral flange area which is designed in particular for the positive and/or non-positive attachment of a further housing element, for example a cover element. According to one embodiment, the flange area is oriented parallel to the arrangement area. The cover element can be made of a metallic or non-metallic material. The use of composite materials can also be advantageous here.

According to a preferred embodiment, the housing element is a lower housing part of an electrical energy storage housing.

The invention also relates to an electrical energy storage housing, comprising a housing element according to the invention, the housing element being a lower housing part, to which an upper housing part is fastened, in particular in a detachable manner.

• - Herstellen eines Gehäuseelements, umfassend einen Anordnungsbereich zur Anordnung einer Vielzahl von Energiespeicherzellen aus einem Verbundmaterial;
• - Verstärken des Anordnungsbereichs durch Anordnen eines Verstärkungselements, insbesondere aus Stahlblech.

The invention also relates to a method for producing a housing element, comprising the steps:

• - producing a housing element, comprising an arrangement region for arranging a plurality of energy storage cells made of a composite material;
• - Reinforcement of the assembly area by arranging a reinforcing element, in particular made of sheet steel.

The steel sheet or the steel layer expediently represents a functional reinforcement of the housing element. The steel layer has good thermal protection in the event of battery cell short circuits, at which temperatures of 1000° C. and more can be reached.

The energy storage cells are preferably attached to the reinforcement element in a materially bonded manner, in particular by means of an adhesive. The reinforcement element preferably has a coating, directed towards the energy storage cells, which serves as an adhesive surface. The coating is, for example, a KTL coating, in particular a coating for corrosion protection, such as a zinc layer or the aforementioned organic coating, which is mentioned in connection with the coated strip material.

According to one embodiment, an intermediate element is arranged on the reinforcement element, according to one embodiment cohesively, the energy storage cells being arranged/attached on the intermediate element, preferably cohesively. The intermediate element, which is preferably plate-shaped, is according to in one embodiment molded or formed from a plastic, for example a foamed plastic such as EPP (expanded polypropylene).

• - Herstellen des Gehäuseelements aus einem faserverstärkten Kunststoff, insbesondere einem Thermoplast, bevorzugt mittels Fließpressen;
• - Anformen, mit anderen Worten Befestigen, des Verstärkungselements beim Formen des Gehäuseelements.

The method preferably comprises the steps:

• - Manufacture of the housing element from a fiber-reinforced plastic, in particular a thermoplastic, preferably by means of extrusion;
• - Molding, in other words fastening, the reinforcing element when molding the housing element.

The features mentioned in connection with the housing element apply analogously and correspondingly to the method, and vice versa.

Further advantages and features result from the following description of embodiments of housing elements with reference to the attached figures.

• 1: eine schematische Draufsicht auf eine Ausführungsform eines Gehäuseelements;
• 2: den Schnitt A-A, wie in der 1 angedeutet.

Show it:

• 1 1: a schematic plan view of an embodiment of a housing element;
• 2 : the cut AA, as in the 1 implied.

1 shows schematically and in a plan view a housing element 1, in this case in particular a lower housing part of an energy storage housing, such as a high-voltage storage device for a motor vehicle, for example for a passenger car. The housing element 1 has an arrangement region 3 in which a reinforcement element 40, particularly preferably a sheet steel, is arranged or fastened. In the present case, the reinforcing element 40, which forms an inner wall 40 in the arrangement area 3, is only partially shown, so that an outer wall 30 of the housing element 1 is visible at least in the lower right area. A flange area 4 is formed circumferentially on the housing element 1, in particular for arranging a housing upper part, not shown here. The housing element 1 comprises a central part 10 and two end parts 20. In the installation position of the housing element 1, the end parts 20 are oriented, for example, in or against the direction of travel. Further functions are expediently integrated into the front parts 20, for example in order to be able to connect vehicle structural components or chassis parts, etc. (not shown here).

The 2 shows the in the 1 outlined section AA in the area of the central part 10. The trough shape of the housing element 1 can be seen in particular. The housing element 1, comprising the central part 10 and two end parts 20, are manufactured integrally as one part or in one piece. Preferred methods are injection molding or extrusion. The use of a composite material as the material for the housing element 1 advantageously allows great freedom of design. In addition, the reinforcement element 40 can expediently be molded on or arranged directly during manufacture.

Reference List

1

Housing element, housing base

3

layout area

4

flange area

10

center part

20

front part

30

outer wall

40

Inner wall, reinforcement element

Claims (13)

Housing element (1) for an energy storage housing, comprising an arrangement area (3) which is designed for the arrangement of a large number of energy storage cells, wherein the housing element (1) is double-walled in the arrangement area (12), comprising an outer wall (30) and an inner wall (40), wherein the outer wall (30) is formed from a composite material, and wherein the inner wall (40) is formed by a reinforcing member (40) disposed on the outer wall (30). housing element claim 1 , wherein the reinforcing element (40) is a steel sheet. housing element claim 1 or 2 wherein the reinforcing member (40) is flat or planar. Housing element according to one of the preceding claims, wherein a ratio of a wall thickness of the inner wall (40) to the outer wall (30) is 0.2 to 0.6. Housing element according to one of the preceding claims, wherein the reinforcing element (40) is attached at least in sections to the outer wall (30) in a positive and/or non-positive and/or material connection. housing element claim 5 , wherein the reinforcing element (40) is formed in the manufacture of the outer wall (30). Housing element according to one of the preceding claims, wherein the composite material is a fiber-reinforced plastic, in particular a long-fiber-reinforced thermoplastic. Housing element according to one of the preceding claims, wherein the housing element is produced by means of extrusion. Housing element according to one of the preceding claims, wherein the housing element (1) is trough-shaped. Housing element according to one of the preceding claims, wherein the housing element (1) is a housing lower part of an electrical energy storage housing. energy storage case, comprising a housing element (1) according to one of the preceding claims, wherein the housing element (1) is a housing bottom part, to which a housing top part is fastened, in particular detachably. Method for producing a housing element (1), comprising the steps: - Manufacturing a housing element (1) from a composite material, comprising an arrangement region (3) for arranging a plurality of energy storage cells; - Reinforcing the arrangement area (3) by arranging a reinforcing element (40), in particular made of sheet steel. procedure after claim 12 comprising the steps of: - producing the housing element (1) from a fiber-reinforced plastic, in particular a thermoplastic, preferably by means of extrusion; - Molding of the reinforcing element (40) when molding the housing element (1).

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