DE102014213306B4 - Battery housing for electric vehicles in the form of a metal-plastic hybrid component and method for its production - Google Patents

Abstract

Battery housing (100), which is designed as a metal-plastic hybrid component, in which a plastic element (102) is formed along a connecting surface (104) to a metal element (101) at least in some areas in a form-fitting and/or cohesive manner, along at least A part of the connecting surface (104) between the metal element (101) and the plastic element (102) is arranged with a connecting element (103) formed with an at least largely permanently elastic material, characterized in that the connecting element (103) with a along at least one part at least one of its surfaces is formed with a permanently elastic material.

Description

The invention relates to a battery housing for electric vehicles in the form of a metal-plastic hybrid component. The invention further relates to a method for producing such a vehicle battery housing.

From the publication DE 10 2006 025 745 A1 is a hybrid housing component, in particular a metal-plastic hybrid oil pan, known in which a metal sealing flange is used, to which a wall area made of plastic material is connected via a connecting strip and a two-sided cohesive connection. An adhesion promoter is provided on both sides of the connecting strip, which creates the cohesive connection between the plastic material of the wall area and the metal material of the sealing flange over the entire surface. The adhesion promoter can be provided over the entire surface or only in certain areas. The metal material can preferably be provided with an adhesion promoter on both sides before processing by punching and deep drawing. It is considered favorable if the adhesion promoter has a certain level of toughness so that it can undergo the required forming steps without detaching from the underlying metal material. The metal material can also only be coated with an adhesion promoter by dipping after punching and deep drawing. In particular, a plastic-based adhesion promoter is used, which serves as a corrosion protection layer when hardened. The plastic material of the wall area can be connected to the sealing flanges using an injection molding process. For this purpose, sheet metal inserts with the sealing flange are inserted into the injection molding tool and injected with the plastic material in a further step.

The adhesion promoter is preferably a two-stage adhesion promoter that completely crosslinks in two successive steps, preferably by thermal activation. After being applied to the metal material, the adhesion promoter is partially cross-linked in a first step, so that a dust-dry surface is formed that is sufficiently resistant to damage during further production steps. During or after plastic injection, the adhesion promoter is completely cross-linked so that it hardens under the influence of temperature and thereby acquires its final properties. The adhesion promoter must, on the one hand, form a cohesive bond with the metal material and, on the other hand, a cohesive bond with the plastic material. Accordingly, its material composition is determined in particular depending on the plastic material used. With some plastic materials, such as B. polystyrene, it may be necessary to pre-treat the metal material with another different adhesion promoter before applying the adhesion promoter in order to achieve a cohesive bond.

However, it turns out that in metal-plastic hybrid components that are exposed to temperature fluctuations during use, especially over a larger temperature range, there are leaks along the connection surfaces, i.e. interfaces between the metal and the plastic, due to the different temperature expansion coefficients of the metal and the plastic Plastic, along which the adhesion promoter is arranged, occur. This leads to failure of the component in metal-plastic hybrid components that must be sealed against liquids and/or gases, such as water or air.

From US 2012/0 015 242 A1 a battery or battery cell is known which can have a housing, a battery cell core accommodated in the housing and at least one terminal which is electrically connected to the cell core and which is electrically connected to the cell core. The battery or cell may also include a lid or sealing plate for sealing the cell core within the housing. The connector can be attached to the lid using a pair of fasteners such as: B. rivets, which are aligned along a longitudinal axis that is offset relative to the terminal so that a portion of the terminal on one side of the axis is larger than a portion of the terminal on the other side of the axis. Such an arrangement may have a relatively large surface area for connection to the terminal. The battery or cell may contain a pair of terminals, each secured to the cover with a pair of fasteners. A clamp may be attached with fasteners that have a size and/or spacing that is different from the size and/or spacing of the fasteners securing the other clamp. Such an arrangement can provide a key-like function for the connections. A gasket and/or insulator may be provided to seal and/or electrically insulate each terminal.

The DE 37 42 026 A1 shows a plastic sealing element for dry batteries. This consists of a rotationally symmetrical centrally perforated base body with a raised edge, onto the top of which an elastomeric sealing material in the form of a circumferential annular bead is sprayed. After pre-assembly of the sealing element with the metal housing cover and assembly of the cell, the annular bead is pressed flat during final flanging so that between The cover and base body create a sealing zone with a small cross-section and extremely long creepage distances. An escape of electrolyte or water vapor, which diffuses into the sealing zone in particular from the porous carbon rod arrester, is thereby reliably prevented.

WO 2011/012 201 A1 shows a battery with a large number of bipolar frame flat cells which are stacked to form the battery. Each of the flat frame cells has two cladding plates. An electrode stack made of anode foils, separator foils and cathode foils is arranged between the cladding sheets. According to the invention, the electrode stack is surrounded by a shielding element. The cladding plates at least partially protrude laterally beyond the shielding element. Around the shielding element, at least in the areas in which the cladding sheets protrude beyond the shielding element, a plastic is applied between the cladding sheets and firmly connected to the cladding sheets. A method for producing such a battery is also described, which is sealed by injection molding, injection compression molding or the like.

The invention has the task of creating an electric vehicle battery housing in the form of a metal-plastic hybrid component of the type described above, in which there are no leaks along the connection surfaces between metal and plastic, even due to temperature fluctuations over a larger temperature range, preferably a few hundred degrees Celsius appear. The invention also has the task of creating a method for producing such a battery housing.

This object is achieved by a battery housing in which a plastic element is formed along a connecting surface to a metal element at least partially, at least largely, in a form-fitting and/or cohesive manner, with a connection along at least part of the connecting surface between the metal element and the plastic element , at least largely, permanently elastic material connecting element is arranged.

In the case of the subject matter of the invention, the plastic element is therefore molded onto the metal element along the connection surface. The connection surface forms the interface between the metal and the plastic. Preferably, the plastic element is formed from a thermoplastic material and formed by injection molding, particularly preferably molded onto the metal element by injection molding. As a result of the molding, the plastic element borders the metal element along the connection surface. The adjoining is at least partially form-fitting and/or cohesive, i.e. at least in areas, i.e. parts, of the connecting surface. According to the invention, a connecting element is now arranged along at least part of this connecting surface, which is formed with an at least largely permanently elastic material. The connecting element thus establishes an at least largely permanently elastic connection between the metal element and the plastic element along this part of this connecting surface and thus creates a reliable seal between the metal element and the plastic element along the connecting surface that is insensitive to temperature fluctuations.

In other words, the plastic element is formed onto the metal element in a largely form-fitting and/or cohesive manner along the connecting surface in a first region, and a connecting element made of permanently elastic material is arranged between the plastic element and the metal element in a second region of the connecting surface

The invention makes use of the knowledge that the known measure of improving the adhesion between the metal element and the plastic element by applying an adhesion promoter to the metal element and thus attempting to further develop the metal-plastic hybrid component in such a way that there are also increased temperature stresses along the connection surface absorb and withstand, does not lead to the desired result or only with disproportionate effort. It turns out that the temperature stresses that occur along the connection surface due to different temperature coefficients of thermal expansion of the metal on the one hand and the plastic on the other hand during thermally changing stress lead to forces along the connection surface that cannot be controlled with the known measures.

Rather, the knowledge now lies in effectively countering the temperature stresses and their harmful effects by creating a targeted opportunity to allow these temperature stresses to be reduced, i.e. the different thermal expansions of metal and plastic as the cause of the occurrence of leaks and thereby counteract possible leaks with special sealing agents. As such sealing means, the invention now proposes to easily replace the bonding agent that is not required with a largely permanently elastic material. The connecting element formed from this creates an at least largely permanently elastic connection between the metal element and the plastic element and thus creates a constructive connection simple and reliable sealing and balancing of temperature stresses along the connection surface.

Preferably, the plastic element is formed as an injection molding element in an injection molding manufacturing process and is also molded onto the metal element by the action of heat and/or pressure, preferably in the injection molding manufacturing process. The permanently elastic material of the connecting element is then designed in such a way that it can withstand the temperatures and pressures of the injection molding manufacturing process when the plastic element is molded onto or around the metal element without changing its mechanical properties. Optionally, it can also be provided that the permanently elastic material of the connecting element is designed in such a way that, as a result of the effect of the temperatures and / or pressures mentioned, it undergoes just such a change as a result of which it is converted into the desired permanently elastic state.

Advantageous embodiments of the battery housing according to the invention are characterized in the subclaims relating back to claim 1.

According to a preferred development of the battery housing according to the invention, the at least largely permanently elastic material of the connecting element comprises a permanently elastic adhesive. This achieves an even better seal along the connection surface and a stronger connection between the metal element and the plastic element. Manufacturing is also advantageously simplified, since the connection element can be applied to the metal element easily, precisely, quickly and safely, and manufacturing errors are avoided due to a change in position, in particular detachment and/or slipping, of the connection element, for example during the injection molding production process when molding the plastic on or around the metal part can be reliably avoided. The adhesive is also designed in such a way that it can either withstand the temperatures and pressures of the injection molding production process without changing its mechanical properties or is transformed into the desired permanently elastic state by the effect of temperature or pressure.

In a further preferred embodiment of the battery housing according to the invention, the connecting element is at least essentially layer-shaped. The connecting element, preferably formed with a permanently elastic adhesive, is thus inserted in layers between the metal element and the plastic element, advantageously with a uniform layer thickness. This design is easy to produce and forms a uniform positive, material and/or frictional connection between the metal element and the plastic element, which results in a high mechanical strength of the battery housing according to the invention and a very reliable seal between metal and plastic.

Such a layered connecting element is designed in a structurally particularly simple and material-saving design exclusively with a permanently elastic adhesive, which is applied, for example, as a paste to the metal element along the connecting surface before the plastic element is molded on.

In the battery housing according to the invention, the connecting element is formed with a support element, preferably a layer-shaped support element, which is provided with permanently elastic material along at least part of at least one of its surfaces. The permanently elastic material is preferably formed again by or with a permanently elastic adhesive. The carrier element is optionally provided on one or more sides, in the case of a layered design on one or both sides, with the permanently elastic material, preferably adhesive. Such a carrier element enables simplified handling of the connecting element during the manufacturing process for the battery housing according to the invention, in particular simplified pre-assembly, since the carrier element in particular gives the connecting element sufficient contour stability for the manufacturing process. The connecting element can therefore be produced separately and precisely and can then be positioned exactly on the connecting surface of the metal element, preferably glued on.

In an advantageous development of the battery housing according to the invention, the carrier element, in particular the layered carrier element, is formed with a film, preferably a plastic film. This design makes it possible to adapt the connection element very flexibly to different designs of the connection surface. For this purpose, the film can be very easily cut, punched or the like and can be easily and easily adapted to different designs of the connecting surface, including different surface shapes of the metal element along the connecting surface, such as curvatures, corrugations, beads, grooves, depressions, etc. The film can be produced easily and inexpensively and can be coated with a permanently elastic material, in particular adhesive, and is easy to handle and process. In a modification, the film itself can be formed with or from a permanently elastic material.

A further preferred embodiment of the battery housing according to the invention is characterized in that the layered carrier element is formed from a thermoplastic material, which can preferably be fused with the thermoplastic material of the plastic element, with the thermoplastic material of the layered carrier element and the thermoplastic material of the plastic element particularly preferably being the same. The carrier element is therefore preferably formed as a plastic film made of a thermoplastic material, which can preferably be fused to the thermoplastic material of the plastic element. The thermoplastic material of the plastic film and the thermoplastic material of the plastic element particularly preferably match. This results in a particularly tight and mechanically strong fusion or welding of the plastics. For this purpose, the plastic film is provided with the permanently elastic material/adhesive in particular only along one of its surfaces, namely along the surface facing the metal element when the connecting element is applied.

According to another embodiment of the battery housing according to the invention, the carrier element is formed with a fabric material. The fabric material is preferably impregnated and/or coated with the permanently elastic material, in particular adhesive. The fabric material gives the carrier element, i.e. the connecting element, high dimensional stability for the manufacturing process of the battery housing according to the invention, but at the same time ensures the flexibility of the connecting element for production and the permanent elasticity of the connecting element in the intended use of the battery housing according to the invention.

• • Herstellen des Metallelements,
• • wahlweise Aufbringen eines flächigen Korrosionsschutzes auf das Metallelement,
• • Aufbringen des Anbindungselements auf das Metallelement entlang wenigstens eines Teils der Anbindungsfläche,
• • Anformen des Kunststoffelements an das Metallelement.

The above-mentioned object is further achieved by a method for producing a battery housing designed in the manner described above in the form of a metal-plastic hybrid component, the method comprising at least the following method steps:

• • Manufacture of the metal element,
• • Optional application of surface corrosion protection to the metal element,
• • Applying the connecting element to the metal element along at least part of the connecting surface,
• • Molding the plastic element onto the metal element.

The production of the metal element in the first step is carried out completely independently of the further process steps. The reduction in temperature stresses ensured by the design of the connecting element according to the invention both during production, for example during cooling after an injection molding production process, and during the intended use of the battery housing according to the invention enables further design freedom than in the prior art, because of the connecting element designed according to the invention larger thermal expansions of the metal element or the plastic element along the connection surface are possible without damage compared to the use of an adhesion promoter. The connection surface therefore no longer needs to be designed with the aim of achieving the lowest possible thermal expansion.

A further advantage is to provide the metal element with corrosion protection over the entire surface, including along the connecting surface, for example with a corrosion protection coating. The permanently elastic material, in particular adhesive, then borders the corrosion protection along the connection surface or adheres to it. Since, according to the invention, this only leads to low mechanical stress on the corrosion protection, its integrity and effectiveness are not impaired.

The connection element can completely or partially cover the connection surface. With partial coverage, a direct positive or material connection and thus a direct adhesion between the metal element and the plastic element is obtained along the parts of the connection surface that are not covered by the connection element, which serves for mechanical strength. However, if the connecting element has the appropriate contour, complete sealing is maintained.

The plastic element is preferably molded onto the metal element in an injection molding manufacturing process of the type mentioned.

The method according to the invention enables simple, cost-effective, precise and safe production of metal-plastic hybrid components designed according to the invention that are tight to gases and liquids, such as air or water.

In the method according to the invention, the connecting element is applied as a paste to the metal element and shaped by this application. The paste can be spread or sprayed or printed if necessary.

Furthermore, the connecting element is provided with a permanently elastic material along at least part of at least one of its surfaces Material-provided carrier element applied to the metal element. In this embodiment, the connecting element is preferably prefabricated, ie prefabricated in the contour that it is intended to assume after it has been applied to the metal element. Preferably, the connecting element is cut and/or punched out in the desired contour from a web-like carrier material, preferably film and/or fabric, which is partially or completely coated with permanently elastic material, in particular adhesive. The individual contours cut out and/or punched out in this way, ie the individual coated carrier elements that form the individual connection elements, can then be applied, in particular glued, to the connection surfaces of the metal elements. In order to simplify the handling of these manufacturing and processing steps and make them automatable, it is particularly preferred to place the individual connecting elements, ie coated carrier elements, after pre-assembly on a protective film or between two protective films, which are in particular strip-shaped. The protective film or films then form a carrier for handling during production and can preferably be rolled up for transport between production sites and production steps. To be applied to the metal elements, the individual connecting elements are removed from the protective film or films and transferred to the connecting surfaces of the metal elements. Optionally, such pre-assembled connecting elements can also be processed by hand.

The present invention is not limited to electric vehicle battery housings, but can of course be transferred to any seal-relevant metal hybrid components.

Brief description of the drawings

• 1 ein Beispiel für ein Metallelement für ein erfindungsgemäß ausgebildetes Batteriegehäuse,
• 2 das erfindungsgemäße Batteriegehäuse, hergestellt mit dem Beispiel für ein Metallelement gemäß 1, und
• 3 eine Schnittdarstellung durch das erfindungsgemäße Batteriegehäuse nach 2 entlang der in 2 eingetragenen Schnittlinie A - A, um 90° gegen den Uhrzeigersinn gedreht.

Embodiments of the invention are shown in the drawing and are described in more detail below, with corresponding elements in all figures being provided with the same reference numerals and a repeated description of these elements being omitted. Show it:

• 1 an example of a metal element for a battery housing designed according to the invention,
• 2 the battery housing according to the invention, manufactured with the example of a metal element according to 1 , and
• 3 a sectional view through the battery housing according to the invention 2 along the in 2 entered cutting line A - A, rotated 90° counterclockwise.

Preferred embodiment of the invention

In 1 The reference numeral 101 denotes a metal element which is intended and designed to form an example of a battery housing according to the invention in the form of a metal-plastic hybrid component 100 and in 1 is shown in detail in a top view. This is a workpiece punched out and deep-drawn from sheet metal for a component to be used in motor vehicle construction. The metal element 101 is provided with several punched openings 110. In the vicinity of the openings 110 and surrounding them, the metal element 101 is intended to be overmolded with a plastic element 102 in an injection molding manufacturing process in order to thereby produce the battery housing 100. The plastic element 102 should be designed in such a way that it borders the metal element 101 at least largely in a form-fitting and/or cohesive manner along a connecting surface 104. The connection surface 104 extends on a top view of the 1 front, i.e. in 1 The first surface 111 of the sheet 101 facing the viewer over the area shown with a border and hatched and surrounds the openings 110 from all sides. In addition, the connection surface also extends on a top view of the 1 posterior, i.e. in 1 the second surface 112 of the sheet metal 101 facing away from the viewer and, strictly speaking, also along the cutting edges of the openings 110 in the sheet metal 101.

2 shows the example of the battery housing 100 according to the invention after carrying out the injection molding manufacturing process, in which the metal element 101 is overmolded with the plastic element 102 along the connection surface 104 and the plastic element 102 is thereby molded onto the metal element. The view of 2 is the same as in 1 , ie a rectangular plan view of the first surface 111 of the metal element 101. All openings 110 of the metal element 101 are covered or enclosed by the plastic element 102, with a passage 113 being formed in the plastic element 102 within the large, circular, middle of the openings 110.

3 shows the battery housing 100 according to the invention 2 in a sectional view along the in 2 entered cutting line A - A, rotated 90° counterclockwise. It can be seen that the plastic element 102 surrounds the cut edges of the openings 110 and the connecting surface 104 also extends along the second surface 112 of the metal element 101 extends. In the example shown, however, the connection surface 104 has smaller lateral dimensions in the area of the second surface 112 than in the area of the first surface 111, ie measured along the surfaces 111 and 112, respectively.

Along the connection surface 104 in the area of the first surface 111, a flat connection element 103 is arranged between the metal element 101 and the plastic element 102 and in 3 also, ie in the same way as the metal element 101 and the plastic element 102, shown in cross section. This connecting element 103 is formed with a permanently elastic material, preferably a permanently elastic adhesive. The permanently elastic material, in particular adhesive, connects positively and/or cohesively to the connecting surface 104 of the metal element 101 on the one hand and to the plastic element 102 on the other hand and forms a permanently elastic seal and positive connection between them, which allows different thermal expansions of the metal element 101 and the Plastic element 102 allows without affecting the tightness of the connection. Along the second surface, the metal element 101 and the plastic element 102 are directly connected to one another in a form-fitting and/or material-locking manner, ie without the interposition of a connecting element 103. This results in a mechanically stronger connection between the metal element 101 and the plastic element 102 than would be the case if the connecting element 103 also extended over the entire surface of the connecting surface 104 in the area of the second surface 112, although such a configuration is also possible in a modification is. Any capillary leaks between the metal element 101 and the plastic element 102 that occur in the area of the second surface 112 along the connection surface 104 are harmless due to the design of the battery housing 100 according to the invention, since the connection element 103 still ensures a reliable seal. Preferably, the connection element 103 is to be provided on the side of the battery housing 100 that is exposed to liquids and/or gases, ie along the edge of the connection surface 104 facing this side, whereby capillary penetration of the liquids and/or gases along the connection surface 104 to the connection element 103 is largely avoided.

To produce the battery housing 100 according to the invention, the connection surface 104 to be overmolded with the plastic element 102 is applied within its sealing area, that is the part of the connection surface 104 along which the connection element 103 is to be formed, i.e. here the connection surface 104 in the area of the first surface 111. A permanently elastic material, here an adhesive, is applied in a predetermined amount, preferably pasty. The amount is calculated so that the tightness to be achieved is guaranteed given the expected temperature fluctuations in the intended use of the battery housing 100, and can be determined, for example, by simple sample production and leak testing. An adhesive specified by the applicant under the name “Acrylic Foam Tape 5363” can be used as such a material. This adhesive is designed to withstand the temperatures encountered during the injection molding manufacturing process, i.e. process temperatures, and pressures for the duration of the injection molding manufacturing process.

In the next manufacturing step, after applying the permanently elastic material, here: adhesive, the metal element 101 is encapsulated with a thermoplastic to produce the plastic element 102. As such a plastic, for example, a plastic specified by the applicant under the name PA6 can be used.

In a modification of this manufacturing process, instead of applying the adhesive in a paste-like manner, a film coated with adhesive is applied to the metal element 101 along the connection surface 104. In particular, a prefabricated connection element 103 is glued as an adhesive film element in the sealing area of the connection surface 104 on the first surface 111 of the metal element 101. Optionally, the prefabricated connection element 103 can be designed as an adhesive tape with a fabric material, for example fabric tape.

Overall, a battery housing in the form of a metal-plastic hybrid component is obtained that meets increased requirements for tightness and temperature resistance and can be produced easily, inexpensively, precisely and quickly and can be reproduced safely and reliably. The battery housing according to the invention enables a high degree of design flexibility. The same applies to metal-plastic hybrid components according to the invention, which can be used, for example, in automotive technology, aerospace technology, medical technology, measurement technology, electronics and in construction

Reference symbol list

100

Battery housing in the form of a metal-plastic hybrid component

101

Metal element of 100

102

Plastic element of 100

103

Connection element of 100

104

Connection area of 101

110

Breakthrough in 101

111

First surface of 101

112

Second surface of 101

113

Implementation in 102 within 110

A-A

Cutting line in 2

Claims (9)

Battery housing (100), which is designed as a metal-plastic hybrid component, in which a plastic element (102) is formed along a connecting surface (104) to a metal element (101) at least in some areas in a form-fitting and/or cohesive manner, along at least A part of the connection surface (104) between the metal element (101) and the plastic element (102) is arranged with a connection element (103) formed with an at least largely permanently elastic material, characterized in that the connection element (103) with a along at least one part at least one of its surfaces is formed with a permanently elastic material. Battery housing (100). Claim 1 characterized in that the carrier element is designed in the form of layers. Battery housing (100). Claim 1 or 2 , characterized in that the at least permanently elastic material of the connecting element (103) comprises a permanently elastic adhesive. Battery housing (100) according to claim 1, 2 or 3, characterized in that the connecting element (103) is at least essentially layer-shaped. Battery housing (100). Claim 1 , characterized in that the carrier element, in particular the layered carrier element, is formed with a film. Battery housing (100). Claim 5 , characterized in that the film is a plastic film. Battery housing (100). Claim 5 , characterized in that the layered carrier element is formed from a thermoplastic material which can preferably be fused to the thermoplastic material of the plastic element (102), the thermoplastic material of the layered carrier element and the thermoplastic material of the plastic element (102) particularly preferably matching. Battery housing (100). Claim 1 , characterized in that the carrier element is formed with a fabric material. Method for producing a battery housing (100) designed according to one of the preceding claims in the form of a metal-plastic hybrid component, characterized by the method steps: • producing the metal element (101), • optionally applying a flat corrosion protection to the metal element (101), • Applying the connecting element (103) to the metal element (101) along at least part of the connecting surface (104) and molding the plastic element (102) onto the metal element (101), characterized in that the connecting element (103) is applied as a paste to the metal element (101) is applied and shaped by this application, and that the connecting element (103) is applied to the metal element (101) as a carrier element provided with permanently elastic material along at least part of at least one of its surfaces.

Images