Joining method for manufacturing a battery housing element for a traction battery of an electric vehicle, battery housing and electric vehicle equipped therewith

Abstract

The invention relates to a joining method for manufacturing a battery housing element (10) for a traction battery of an electric vehicle, in which two components (14, 16) are foamed together over a surface, wherein a foam material is introduced into a cavity (24) between the two components (14, 16) and both components are joined in a press tool (21a, 21b), characterized by the following process steps: - Providing at least one injection opening (28) as access to the cavity (24) in one of the components (14, 16) for injecting liquid foam material (29); - Transferring the components (14, 16) into the press tool (21a, 21b); - Joining the two components (14, 16); - Injecting the liquid foam material (29) through the injection opening (28) to fill the cavity (24); - Leaving the battery housing element (10) in the press tool (21a, 21b) until the end of a foaming reaction time of the foam material (29). The invention also relates to a battery housing element produced by the method and to an electric vehicle equipped with such a battery housing element. This allows the use of foam materials with shorter open times, resulting in faster reaction processes and reduced cycle times. The injection process does not produce the contamination associated with conventional methods.

Description

[0001] The invention relates to a joining method for manufacturing a battery housing element for a traction battery of an electric vehicle, in which two components are foamed together over their entire surface, wherein a foam is introduced into a cavity between the two components and both components are joined in a press tool. The invention also relates to a battery housing element manufactured by means of the method and to an electric vehicle equipped with such a battery housing element.

[0002] A process for manufacturing a battery housing element is known from DE 10 2020 007 002 A1. In this process, one of two components to be joined is placed in the press tool, and then a liquid foam material is introduced into the open cavity. The cavity is then closed by attaching and fixing the second component using the press tool, whereby the foam subsequently expands and completely fills the cavity. The injection of the liquid foam into the lower housing component causes significant contamination of the system due to overspray. Since the foam typically contains hazardous substances such as isocyanates, strict occupational safety requirements must be met, which, in addition to increased manufacturing effort, results in a longer cycle time.

[0003] The object of the invention is to provide a method for manufacturing a battery housing element for a traction battery of an electric vehicle from two housing components by means of foaming, which is characterized by reduced manufacturing effort and shortened cycle times.

[0004] The invention is defined by the features of the independent claim. Advantageous further developments and embodiments are the subject of the dependent claims.

[0005] The problem is solved according to claim 1 by a method comprising the following process steps: - Providing at least one injection port as access to the cavity in one of the components for injecting liquid foam material; - Placing the components in the press tool; - Joining the two components; - Injecting the liquid foam material through the injection opening to fill the cavity; - Leaving the battery casing in the press tool until the foaming reaction of the foam material has ended.

[0006] The components are preferably joined using an adhesive that is applied to one of the parts and allowed to cure after joining. Alternatively, other joining methods such as welding, soldering, screwing, or riveting can be used, although these would be considerably more complex.

[0007] The solution according to the invention consists of first joining the two components in a press tool without the foam, and then injecting the foam. The resulting rapid foam distribution allows the use of foam materials with significantly shorter open times. The direct consequence is that subsequent reaction processes also proceed faster, and cycle times can be reduced. The injection process does not produce any contamination (so-called overspray) as with conventional methods. This eliminates the need for time-consuming masking steps, prevents equipment contamination, and makes the stringent safety precautions required during the spraying process unnecessary. Compared to previously used functional foams, a material with improved flowability and reactivity can be used for injection.

[0008] According to an advantageous embodiment of the invention, a seal is provided on the circumferential edge of the cavity on one of the two components before joining. Such a seal prevents the foam from escaping laterally between the components to be joined. Preferably, the seal is applied as a bead of sealant, and more preferably on the component located at the bottom of the press tool. Alternatively, the seal can be applied as adhesive tape.

[0009] According to an advantageous embodiment of the invention, the cavity is evacuated before the foam material is injected. For this purpose, at least one evacuation opening is provided in one of the components, through which the cavity is evacuated to a pressure of approximately 100-400 hPa after the components have been joined, in order to draw the injected foam material into all cavities of the cavity and thus ensure complete filling of the cavity.

[0010] According to an advantageous embodiment of the invention, the foaming reaction generates a pressure on the order of about 1 - 2 bar in the cavity, which smooths at least one of the components.

[0011] According to an advantageous embodiment of the invention, a housing top part of a battery housing for a traction battery of an electric vehicle is produced using the joining method according to the invention. This housing top part comprises a reinforcement plate and a battery cooling element. The battery cooling element is designed as a cover plate to be arranged above the traction battery, which has cooling channels on the side facing away from the traction battery, i.e., within the cavity. The cover plate is connected to a spaced-apart reinforcement plate by means of a foaming process. In the assembled state, the passenger compartment of the vehicle is located above the reinforcement plate.

[0012] Similarly, a lower housing part of a battery housing for a traction battery can also be manufactured, consisting of an outer part and an inner part foamed with it.

[0013] According to an advantageous embodiment of the invention, an electric vehicle is provided with a battery housing, the upper part of which and / or the lower part of which is manufactured according to the method according to the invention.

[0014] Further advantages, features, and details will become apparent from the following description, in which – possibly with reference to the drawings – at least one embodiment is described in detail. Identical, similar, and / or functionally equivalent parts are identified by the same reference numerals.

[0015] They show: Fig. 1: a schematic, perspective representation of two components to be joined to form a battery housing element; Fig. 2: a schematic, perspective representation of the two components after the joining process; Fig. 3: the representation of Fig. 3 after completion of the injection process; Fig. 4a: a section of the component from the previous figures before the foaming process has ended; Fig. 4b: the excerpt from Fig. 4a after the foaming process has ended.

[0016] In Fig. Figure 1 shows two components of a battery housing element to be manufactured for a traction battery of an electrically powered vehicle, in this case a housing upper part 10, which consists of a battery cooling element 12 and a reinforcement plate 14. The battery cooling element 12, in turn, consists of a battery frame 16 and a battery cover 18, on the rear of which a plurality of cooling channels 20 are formed. The housing upper part 10 is mounted on the vehicle in reverse order as shown in the figures, i.e., the reinforcement plate 14 shown below forms the top of the housing upper part 10 in the mounted state, and the vehicle's traction battery (not shown) is located below the battery cover 18 in the mounted state.

[0017] To carry out the joining method according to the invention, the reinforcement plate 14 is placed in a press tool (not shown) with two [unclear] Fig. The four dies 21a and 21b shown are placed in the dies. Subsequently (or also beforehand), a seal 22 is attached to the reinforcement plate 14 (alternatively to the battery cooling element 12), and an adhesive (not shown) is applied to one of the joining surfaces of the reinforcement plate 14 and the battery cooling element 12. Then, by joining the two surfaces, the components are joined together. Fig. The two components 12, 18 of the housing upper part 10 are joined in the die shapes 21a, 21b of the press tool shown in Figure 4, whereby the components are bonded together. Fig. Figure 2 shows this state. The surfaces of the reinforcement plate 14 and the battery cooling element 12 are spaced apart from each other and form a cavity (hollow space) 24 between them, which extends circumferentially to the seal 22.

[0018] Cavity 24 is connected to the environment via two openings: an evacuation opening 26 for evacuating cavity 24 and an injection opening 28 for injecting foam material 29. The evacuation opening 26 is airtightly connected to an evacuation unit (not shown), which reduces the air pressure in cavity 24 to a very low value of 100–400 hPa. As shown in Fig. As shown in Figure 3, liquid foam material is injected into the cavity 24 via the injection opening 28. Within a residence time of 5–20 seconds, the foam spreads, aided by the negative pressure in the floor of the entire cavity 24, up to the seal 22, as indicated by the first arrows 30. The foam then expands within a rise time of approximately 15–60 seconds and fills the entire cavity 24. As shown in Fig. 3 with the second arrows 32, is indicated by means of the in Fig. The die shapes 21a, 21b shown in Figure 4 generate a counter-pressure on the cavity 24, which counteracts deformation of the components 12, 14 by the expanding foam. Conversely, the internal pressure of approximately 1 to 3 bar generated by the foam against the die shapes 21a, 21b causes the plates 14, 18 to smooth, which in the Fig. 4a and Fig. 4b is shown.

[0019] Fig. Figure 4a shows the state before the swelling of the still liquid foam material 29 with a reinforcing plate 14, which has several irregularities 34. In Fig. Figure 4b shows the state after the end of the rise time, i.e., after the completion of the foaming process, whereby the reinforcement plate 14 now lies flat and smooth against the lower die 21b, which is caused by the swelling foam and the pressure generated by it.

[0020] A reaction time of several minutes then ensues until the foam has chemically reacted and solidified. Following this, the finished battery housing element 10 can be removed from the separated dies 21a, 21b.

[0021] Although the invention has been further illustrated and explained in detail by means of preferred embodiments, the invention is not limited by the disclosed examples, and other variations can be derived from them by a person skilled in the art without departing from the scope of protection of the invention. It is therefore clear that a multitude of possible variations exist. It is also clear that the embodiments mentioned as examples are truly only examples and are not to be understood in any way as limiting, for example, the scope of protection, the possible applications, or the configuration of the invention.Rather, the preceding description and the description of the figures enable the person skilled in the art to implement the exemplary embodiments in concrete terms, whereby the person skilled in the art, with knowledge of the disclosed inventive concept, can make various changes, for example with regard to the function or the arrangement of individual elements mentioned in an exemplary embodiment, without leaving the scope of protection defined by the claims and their legal equivalents, such as further explanations in the description. Reference symbol list 10 Battery housing element 12 Battery cooling element 14 Reinforcement plate 16 battery frames 18 Battery cover 20 cooling channels 21a,b Die forms 22 Seal 24 cavities 26 Evacuation opening 28 Injection port 29 foam material 30 first arrows (foam spreading directions) 32 second arrows (pressure of the die forms) 34 surveys QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2020 007 002 A1

[0002]

Claims

[1] Joining method for manufacturing a battery housing element (10) for a traction battery of an electric vehicle, in which two components (14, 16) are foamed together over a surface, wherein a foam material is introduced into a cavity (24) between the two components (14, 16) and both components are joined in a press tool (21a, 21b), characterized by the following procedural steps: - Providing at least one injection opening (28) as access to the cavity (24) in one of the components (14, 16) for injecting liquid foam material (29); - Transferring the components (14, 16) into the press tool (21a, 21b); - Joining the two components (14, 16); - Injecting the liquid foam material (29) through the injection opening (28) to fill the cavity (24); - Leaving the battery housing element (10) in the press tool (21a, 21b) until the end of a foaming reaction time of the foam material (29). [2] Joining method according to claim 1, characterized by , that before joining a seal (22) is arranged on the circumferential edge of the cavity (24) on one of the two components (14, 16). [3] Joining method according to claim 2, characterized by , that the seal (22) is applied as an applied sealing bead. [4] Joining method according to any of the preceding claims, characterized by , that the cavity (24) is evacuated before the injection of the foam material (29). [5] Joining method according to any of the preceding claims, characterized by , that the foaming reaction generates a pressure in the cavity (24) which causes a smoothing of at least one of the components (14, 16). [6] Battery housing upper part (10) comprising a reinforcement plate (14) and a battery cooling element (12) foamed over its surface, characterized by that this is produced by means of the joining process according to one of claims 1 to 5. [7] Battery housing lower part comprising an outer part and an inner part foamed over the entire surface therewith, characterized by that this is produced by means of the joining process according to one of claims 1 to 5. [8] Electric vehicle comprising a battery housing element (10) according to claim 6 and / or 7.

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