BATTERY HOUSING FOR A VEHICLE BATTERY

Description

[0001] The invention relates to a battery housing for a vehicle battery, comprising a housing part with a circumferential sealing flange and a housing cover having a circumferential seal that seals a contact edge formed between the sealing flange and the housing cover. The invention further relates to a method for producing such a battery housing and to a vehicle battery having such a battery housing.

[0002] Electric or electric-powered vehicles, such as electric or hybrid vehicles, typically include an electric motor that can drive one or both axles. To supply electrical energy, the electric motor is typically connected to an on-board (high-voltage) battery that serves as an electrical energy storage device.

[0003] An electrochemical battery, in particular, is understood here and below to mean a so-called secondary battery (secondary battery) of a motor vehicle. In such a (secondary) vehicle battery, consumed chemical energy can be recovered by means of an electrical charging process. Such vehicle batteries are designed, for example, as electrochemical accumulators, in particular as lithium-ion accumulators. To generate or provide a sufficiently high operating voltage, such vehicle batteries typically have at least one battery module in which several individual battery cells are interconnected in a modular manner.

[0004] The battery cells or battery modules are typically housed in a battery housing of the vehicle battery. Such battery housings generally comprise a housing section with a circumferential sealing flange, which can be closed with a housing cover. A circumferential seal is typically provided between the housing cover and the sealing flange. This seal protects the interior of the housing, i.e., the battery cells or battery modules, from the ingress of moisture and / or dirt, and also prevents the escape of chemicals in the event of damage to one or more battery cells. The necessary sealing pressure is generally achieved by screwing or riveting the housing cover and the sealing flange.

[0005] The battery housing seal essentially serves to ensure the tightness of the battery housing throughout the service life of the vehicle battery or motor vehicle. For this purpose, battery housings are typically tested and inspected for leaks using positive and negative pressure after assembly.

[0006] Possible seals include molded seals made of plastic or rubber materials, such as EPDM (ethylene propylene diene rubber), NBR (acrylonitrile or nitrile butadiene rubber), or silicone foam. Such molded seals are typically manufactured as one-piece, i.e., monolithic, molded parts, which are placed as an insert seal between the housing cover and the sealing flange. For larger battery housings, correspondingly larger molded seals are necessary, which makes them more difficult to handle during assembly. This, in turn, adversely increases the risk of errors during assembly.

[0007] A seal in the form of a sealing cord or sealing strip made of an elastomer, particularly silicone rubber, is also possible. However, such sealing cords require a comparatively large sealing flange as a contact surface, which adversely limits the available installation space for the battery cells within the battery housing. In other words, the use of a sealing cord adversely reduces the energy capacity of the battery module or battery cells. Furthermore, the handling of sealing cords is also more difficult in larger battery housings, resulting in an increased susceptibility to errors during assembly.

[0008] Furthermore, adhesive joints, such as those made of PU (polyurethane) adhesive, are also conceivable as housing seals. A "material bond" or "material bond" between at least two interconnected parts is understood here and below to mean, in particular, that the interconnected parts are held together at their contact surfaces by material bonding or cross-linking (e.g., due to atomic or molecular bonding forces), possibly with the aid of an additive.

[0009] Such adhesive seams require comparatively long curing times during assembly, which adversely extends the production time of such vehicle batteries.

[0010] Furthermore, such adhesive seams are susceptible to fluctuating process parameters such as room temperature, humidity, or surface quality of the application surfaces during application or application to the housing cover and / or the sealing flange. Therefore, it is necessary to control and / or regulate such process parameters during application, which adversely increases the manufacturing costs of the battery housing. Such adhesive seams also have the disadvantage that the adhesive seam cannot be removed without causing damage during maintenance or repair of the vehicle battery.

[0011] When assembled, the housing cover and the housing part are fastened together. The seal is typically located in the area of ​​a radially inner contact edge between the sealing flange and the housing cover, with the housing cover and the housing part resting on one another radially outside of the seal. This joint gap or joint zone between the superimposed housing halves is also referred to as the zero-gap area.

[0012] Here and in the following, "zero gap area" refers in particular to the technical zero gap between the housing halves, i.e., the remaining gap between the two housing halves to be joined. This gap is referred to, for example, as a gap with a width of zero, although, due to manufacturing tolerances or surface irregularities or roughnesses, a residual gap with a width in the range of several micrometers may exist between the housing halves. In other words, the zero gap area is the area between the housing halves in which the components would lie flat or flat, i.e., directly and gap-free, on top of each other, if there were no surface irregularities or roughnesses on the contact surfaces of the components during production.

[0013] Unfortunately, during operation of the vehicle battery, an electrolyte, such as water, can penetrate this zero-gap area. Seals of the type described above are therefore at risk of what is known as corrosive infiltration, in which the electrolyte, starting from the zero-gap area, attacks the surface of the sealing flange and / or the housing cover and infiltrates the seal, causing the seal to no longer function as a seal against the battery housing, thus leading to unwanted leaks.

[0014] To prevent such corrosive infiltration, it is conceivable, for example, to design the seal as a permanently plastic seal. A permanently plastic seal is understood in particular to be a sealant that permanently has a putty-like, plastic consistency. In other words, such a permanently plastic sealant does not harden.

[0015] Such permanently plastic seals, which are also referred to as liquid seals, however, disadvantageously require very precisely machined sealing surfaces, i.e., a high surface quality of the housing cover and the sealing flange with minimal fluctuations in manufacturing tolerance. Such sealing surfaces are generally not present in vehicle batteries, as the housing covers, for example, are conventionally designed as a deep-drawn component. This requires additional processing steps, such as milling and / or polishing the contact surfaces of the housing cover, which would make the production of such a vehicle battery significantly more complex and costly.

[0016] US 2014 / 246259 A1 describes a vehicle battery with a battery housing. The battery housing comprises two housing parts die-cast from an aluminum alloy with a plurality of cooling fins. These cooling fins improve heat dissipation properties and also serve to protect the corners of a lower part of the vehicle battery in the event of an impact with a curb or the like. The cooling fins are provided on both sides of a safety valve to protect the safety valve from impact.

[0017] DE 10 2016 107369 A1 discloses a high-voltage battery with a battery housing comprising a receiving space for battery cells, which can be tightly closed by a cover using an adhesive bond with a seal formed from an adhesive. A cutting thread, which is laid parallel to the seal, serves to release the adhesive bond as needed.

[0018] US 2015 / 207119 A1 describes a battery housing with a lower frame and a top cover. A battery module is arranged in the lower frame of the battery housing. The top cover is firmly connected to the lower frame via a sealing element that extends continuously over the entire circumference of the respective outer peripheral edge portion of the top cover.

[0019] DE 10 2012 218188 A1 discloses a housing for a battery cell. The housing consists of a container and a lid assembly, wherein the lid assembly includes, among other things, a cover plate, which is firmly connected to the container after the insertion of internal components of the battery cell. The cover plate is bonded, for example, along a projection to an inner surface of the container using a layer of adhesive. A sealing bead of a sealing assembly, formed, for example, by an O-ring, prevents electrolyte introduced into the housing from coming into contact with the adhesive and chemically attacking it.

[0020] The invention is based on the object of providing a particularly suitable battery housing for a vehicle battery. In particular, the risk of corrosive infiltration of the (housing) seal is to be completely avoided or at least significantly reduced. The invention is further based on the object of providing a particularly suitable method for producing such a battery housing, a particularly suitable vehicle battery, and a particularly suitable use of a liquid sealant for corrosion protection.

[0021] The object is achieved according to the invention with regard to the battery housing by the features of claim 1, with regard to the method by the features of claim 7, and with regard to the vehicle battery by the features of claim 9. Advantageous embodiments and refinements are the subject of the respective subclaims. The advantages and embodiments cited with regard to the battery housing are also transferable mutatis mutandis to the method and / or the vehicle battery and / or the use, and vice versa.

[0022] The battery housing according to the invention is suitable and configured for a vehicle battery. The battery housing comprises two housing halves joined to form a closed housing. The first housing half is designed as a housing part (lower shell) and has, for example, a number of battery compartments or receptacles for battery cells. The housing part has a circumferential sealing flange. Here and below, a sealing flange is to be understood in particular as an end-face or axial contact surface of the side walls of the housing part, on which the second housing part rests at least partially. The second housing half is designed as a housing cover (battery cover, upper shell). The housing cover has a circumferential seal which seals a contact edge formed between the sealing flange and the housing cover, preferably in a leak-free and fluid-tight manner.

[0023] Radially outside the seal, i.e., from the contact edge to the exterior of the battery housing, a zero-gap area, meaning a technically zero-gap area, is formed between the housing cover and the sealing flange. According to the invention, a liquid seal is incorporated into the zero-gap area. This means that, in addition to the radially inner seal, a second seal in the form of a liquid seal is provided, arranged radially outside for this purpose. The liquid seal prevents electrolyte or water from penetrating the zero-gap area, thus preventing the radially outer area in front of the seal from being corroded.

[0024] The gasket and the liquid sealant work together as a battery cover seal with corrosion protection, providing a reliable and operationally safe seal, especially for larger battery cases. This enables a particularly suitable, fluid-tight, and leak-free battery case, in which the risk of corrosive infiltration of the seal is advantageously reduced or completely eliminated.

[0025] The combined use of the seal and the liquid seal according to the invention results in a particularly suitable battery housing. The liquid seal prevents the penetration of electrolyte into the zero-gap area in a simple and cost-effective manner, so that the sealing effect of the seal is essentially guaranteed over the entire service life of the vehicle battery. The liquid seal therefore essentially serves only to protect the zero-gap area from corrosion and not to seal the battery housing. This enables a reduction in manufacturing tolerances of the housing halves, since essentially only the inner seal is used for sealing. In particular, no additional and complex machining steps of the contact surfaces are necessary.

[0026] The seal is particularly fluid- and chemical-resistant, ensuring reliable sealing against incoming liquids and escaping (battery) chemicals. The liquid seal is particularly electrolyte- and water-resistant and essentially acts as corrosion protection for the adjacent housing surfaces in the zero-gap area. In other words, the liquid seal is specifically designed for media contact with an electrolyte or water. For example, the liquid seal is designed as a synthetic, permanently plastic sealant, such as Drei Bond 1108.

[0027] In an advantageous embodiment, the liquid seal essentially completely fills the zero-gap area. This ensures that no electrolyte can penetrate into the zero-gap area, thus essentially completely eliminating the risk of corrosive infiltration of the seal.

[0028] The seal can be designed, for example, as a molded or cord seal. However, in a practical embodiment, the seal is designed as a foam seal, i.e., a molded seal or sealing seam in the form of a foamed plastic material. The seal is made, for example, from polyurethane or silicone foam. This creates a seal that is simple and cost-effective to manufacture.

[0029] In a conceivable further development, the housing cover is frictionally joined to the sealing flange at a number of fastening points. This allows for simple and effort-reduced attachment of the housing cover to the housing part, ensuring reliable and operationally safe sealing pressure for the contact edge seal.

[0030] A "positive connection" or "positive connection" between at least two interconnected parts is understood here and below to mean, in particular, that the interconnected parts are prevented from sliding against each other due to a frictional force acting between them. If a "connecting force" causing this frictional force (this means the force that presses the parts against each other, for example, a screw force or the force of gravity itself) is absent, the positive connection cannot be maintained and can therefore be released.

[0031] The fastening points press the housing cover and the sealing flange together or clamp them directly against each other. The force-locking connection is preferably designed as a screw connection. For example, the housing cover has a number of recesses arranged one above the other in axial alignment with the threaded holes in the sealing flange. A fastening screw is guided through each recess and screwed or threaded into the respective threaded hole.

[0032] The method according to the invention is suitable and designed for producing a battery housing as described above. According to the method, in addition to the seal at the contact edge, a liquid seal is also applied to the housing cover and / or the sealing flange in the zero-gap area before the housing cover is joined to the sealing flange. The conjunction "and / or" is to be understood here and below in such a way that the features linked by this conjunction can be implemented both jointly and as alternatives to one another.

[0033] In one conceivable embodiment, for example, a sprayable sealant is used as a liquid sealant, which is preferably applied as a spray mist to the housing cover and / or the sealing flange. A sprayable sealant is understood in particular to mean a sealant that can be atomized or distributed as an aerosol.

[0034] In a preferred embodiment of the method, the liquid sealant is applied as a pasty, particularly permanently plastic, sealant. Such a pasty liquid sealant enables automated, time-reduced, and—in terms of quantity and positioning—very precise application of the liquid sealant. Furthermore, no soiling or contamination from spray mist occurs during the production of the battery housing, thus eliminating the need for additional encapsulation of an application system.

[0035] The liquid gasket can, for example, be applied in a straight line to the housing cover and / or the sealing flange. However, in a suitable refinement, the liquid gasket is applied to the housing cover and / or the sealing flange in a bead-like or meander-like pattern. This ensures a particularly even distribution of the liquid gasket in the zero-gap area.

[0036] In a preferred embodiment of the method, the housing cover is joined to the sealing flange after the liquid gasket has been applied. This means that the liquid gasket is produced using an FIP (formed in place) process, in which the liquid gasket is applied in liquid form and the housing halves are then joined together. The distribution of the liquid gasket in the zero-gap region therefore preferably takes place during and / or after the housing halves are joined. By joining or pressing the housing halves together, the liquid gasket is distributed essentially over the entire surface in the zero-gap region. This means that the contact surfaces of the housing cover and the sealing flange are essentially completely wetted by the liquid gasket, even if the liquid gasket is only applied to one of the housing halves.This enables particularly reliable corrosion protection to be achieved to prevent corrosive infiltration of the seal.

[0037] This ensures that the liquid gasket always has an optimal fit in the zero-gap area, as it forms itself due to the contact pressure during assembly. After setting or curing, this creates a particularly electrolyte-impermeable and corrosion-protected bond between the housing cover and the sealing flange.

[0038] In a preferred application, the battery housing is part of a vehicle battery of an electrically powered or drivable motor vehicle, in particular an electric or hybrid vehicle. This results in a particularly suitable, reliable, and long-lasting vehicle battery.

[0039] A non-inventive aspect of the invention provides for the use of a liquid gasket as corrosion protection for a zero-gap area between a housing cover and a sealing flange of a housing part of a battery housing. The zero-gap area is arranged radially outwardly of a seal of the battery housing, so that the corrosion protection of the liquid gasket prevents corrosive infiltration of the seal.

[0040] Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. In the drawings: Fig. 1 shows a perspective view of a vehicle battery with a battery housing, Fig. 2 shows a perspective view of a section of the battery housing, Fig. 3 shows a sectional view of the battery housing along the section line III-III according to Fig. 2 , Fig. 4 in sectional view the battery housing along the section line IV-IV according to Fig. 2, Fig. 5 in plan view, a section of a housing part of the battery housing with a sealing flange and a liquid sealant applied thereon in a bead-like manner, Fig. 6 in plan view, a section of the sealing flange with a pasty liquid sealant applied thereon, and Fig. 7 in plan view, a section of the sealing flange with a sprayable liquid sealant applied thereon.

[0041] Corresponding parts and sizes are always provided with the same reference symbols in all figures.

[0042] The Fig. 1shows a perspective view of a vehicle battery 2 for an electrically powered or drivable motor vehicle (not shown in detail). In the installed state, the vehicle battery 2 is arranged in a battery installation space of the motor vehicle. The battery installation space is open, for example, on the underside and bounded by a vehicle underbody. In other words, the vehicle battery can be mounted or installed, in particular, from the underside of the vehicle.

[0043] The vehicle battery 2 has a battery housing 4. A number of battery modules or battery cells (not shown in detail) are arranged and interconnected in the battery housing 4 as electrochemical energy storage devices. The battery housing 4 has a housing part 6 and a housing cover 8 that closes or covers the housing. The housing cover 8 is, for example, a deep-drawn sheet metal part.

[0044] The approximately rectangular housing part 6 has four axially upstanding side walls which enclose the interior of the battery housing 4. The housing cover 8 rests essentially on the front side on these side walls, wherein the contact surfaces of the side walls facing the housing cover 8 are also referred to below as sealing flanges 10 ( Fig. 3 ) of the housing part 6.

[0045] As shown in the enlarged view of the Fig. 2 As can be seen in detail, the housing cover 8 is joined to the sealing flange 10 or the housing part 6 in a force-fitting manner at several fastening points 12 distributed around the circumference. The fastening points 12 are designed in particular as screw connections and are provided with reference numerals in the figures merely as examples.

[0046] The Figures 3 and 4show a sectional view of the battery housing 4 along the section line III-III or IV-IV according to Fig. 2 . The section line III-III runs through the fastening point 12, whereby the section line IV-IV is arranged between two fastening points 12.

[0047] As shown in the schematic and simplified representations of the Fig. 3 and the Fig. 4 As can be seen comparatively clearly, the housing cover 6 has a circumferential seal 14, which seals a contact edge 16 formed between the sealing flange 10 and the housing cover 6 in a leak-free and fluid-tight manner. The seal 14 is designed, for example, as a foam seal, in particular as a molded seal or sealing seam in the form of a foamed plastic material. The seal 14 is made, for example, from a polyurethane or silicone foam and is molded onto the housing cover 8, in particular using an injection molding process.

[0048] The peripheral seal 14 is subjected to axial sealing pressure by the fastening points 12 and is at least partially compressed. The fastening points 12 each have a fastening screw 18 that extends through the housing cover 6 and is screwed into the sealing flange 10 or the housing part 6.

[0049] Radially outwardly of the seal 14 or the contact edge 16, i.e., toward the exterior of the battery housing 4, a zero-gap region 20 is formed between the housing cover 6 and the sealing flange 10. As shown schematically in the figures, a liquid seal 22 is introduced into the zero-gap region 20, essentially completely filling it. The liquid seal 22 prevents electrolyte or water from penetrating the zero-gap region 20, whereby the radially outer region in front of the seal 14 is not susceptible to corrosion by the electrolyte. The seal 14 and the liquid seal 22 act together as a battery cover seal with a corrosion protection function.

[0050] The seal 14 is made of a fluid- and chemical-resistant material, wherein the liquid seal 22 is made of a material that is particularly electrolyte-resistant, in particular water-resistant.

[0051] The following is based on the Figures 5 to 7 a method for producing the battery housing 4 is explained in more detail.

[0052] According to the method, the liquid seal 22 is applied or applied to the sealing flange 10 in the zero gap area 20 radially outside the seal 14 before the housing cover 8 is joined to the sealing flange 10 ( Fig. 5 ). Additionally or alternatively, it is also conceivable, for example, that the liquid seal 22 is applied to the housing cover 8.

[0053] After the liquid gasket 22 has been applied or applied, the housing cover 6 is screwed to the sealing flange 10. This means that the liquid gasket 22 is essentially manufactured using a FIP (formed in place) process. This ensures that the liquid gasket 22 always has an optimal fit in the zero-gap area 20, as it forms itself due to the contact pressure during assembly. The liquid gasket 22 is suitably applied to the sealing flange 10 in a bead-like or meander-like pattern, ensuring the most even wetting and filling of the zero-gap area 20 when the housing cover 6 is pressed or screwed onto the sealing flange 10. This creates an electrolyte-impermeable and corrosion-protected connection between the housing cover 8 and the sealing flange 10 in the zero-gap area 22.

[0054] In the Fig. 6The liquid sealant 22 is applied as a pasty sealant. Such a pasty liquid sealant 22 enables automated and time-reduced application, as well as very precise application in terms of quantity and position.

[0055] The Fig. 7 The embodiment shown shows a liquid seal 22 in the form of a sprayable sealant, which is applied as a spray mist onto the sealing flange 10 in the zero gap area 20.

[0056] The claimed invention is not limited to the exemplary embodiments described above. Rather, other variants of the invention can also be derived therefrom by those skilled in the art within the scope of the disclosed claims without departing from the subject matter of the claimed invention. In particular, all individual features described in connection with the various exemplary embodiments can be combined within the scope of the disclosed claims without departing from the subject matter of the claimed invention. List of reference symbols

[0057] 2Vehicle battery 4Battery housing 6Housing part 8Housing cover 10Sealing flange 12Fastening point 14Seal 16Contact edge 18Fastening screw 20Zero gap area 22Liquid seal

Claims

1. Battery housing (4) for a vehicle battery (2), comprising a housing part (6) which has a peripheral sealing flange (10), and a housing cover (8) which has a peripheral seal (14) which seals a contact edge (16) formed between the sealing flange (10) and the housing cover (6), - wherein a zero-gap region (20) is formed radially on the outside of the seal (14), between the housing cover (6) and the sealing flange (10), and - wherein a liquid seal (22) is introduced into the zero-gap region (20).

2. Battery housing (4) according to claim 1, characterized in that the liquid seal (22) substantially completely fills the zero-gap region (20).

3. Battery housing (4) according to claim 1 or claim 2, characterized in that the seal (14) is a foam seal.

4. Battery housing (4) according to any of claims 1 to 3, characterized in that the housing cover (8) is joined in a force-fitting manner to the sealing flange (10) at a number of fastening points (12).

5. Method for producing a battery housing (4) according to any of claims 1 to 4, wherein a liquid seal (22) is applied to the housing cover (8) and / or the sealing flange (10) in the zero-gap region (20) before the housing cover (8) is joined to the sealing flange (10).

6. Method according to claim 5, characterized in that a pasty sealant is applied as a liquid seal (22).

7. Method according to claim 5 or claim 6, characterized in that the liquid seal (22) is applied in a beaded or meandering manner to the housing cover (8) and / or the sealing flange (10).

8. Method according to any of claims 5 to 7, characterized in that the liquid seal (22) is distributed in the zero-gap region (20) during the joining of the housing cover (8) to the sealing flange (10).

9. Vehicle battery (2) of an electrically driven or drivable motor vehicle, comprising a battery housing (4) according to any of claims 1 to 4.