Vehicle battery for a motor vehicle as well as motor vehicle

Abstract

Vehicle battery (3) for a motor vehicle (1), in particular an electrically powered motor vehicle (1), with a battery housing (10) in which at least one cell pack (4) with at least one battery cell (5) is arranged, wherein the battery housing (10) is formed by a hollow profile strand (11), characterized in that the battery housing (10) designed as a hollow profile strand (11) has four wall sections (16a-d) extending over the entire length of the hollow profile strand (11) and curved outwards towards the housing, with a bridge-arch-like profile seen in the cross-section of the hollow profile strand (11), wherein the curvature (17) of the wall sections (16a-d) is homogeneously formed over the entire length of the hollow profile strand (11).

Description

The invention relates to a vehicle battery for a motor vehicle according to the preamble of claim 1 of the invention. According to claim 9 of the invention, it further relates to a motor vehicle, in particular an electrically powered motor vehicle, with such a vehicle battery. In recent years, due to the ever-decreasing supply of fuels for internal combustion engines, significant efforts have been made to develop alternative drive systems. Electric drive systems, powered by one or more electrical storage devices such as accumulators or batteries, are gaining increasing importance. A vehicle can be powered exclusively by one or more electric motors or, as a hybrid vehicle, by both an internal combustion engine and one or more electric motors. Lithium-ion batteries are increasingly favored by experts as traction batteries, which offer the advantages of no memory effect and low self-discharge.When using lithium-ion batteries in particular, the potential hazards they pose should not be underestimated. For example, mechanical damage to the battery casing, such as that resulting from a vehicle crash, can lead to internal short circuits, and excessive current can cause the casing housing the batteries to melt and catch fire. All these uncertainties necessitate special safety measures to ensure the safe operation and production of electric vehicles. German patent application DE 10 2016 115 647 B3 discloses a battery carrier for mounting at least one battery in an electric vehicle. This carrier features a tray for receiving the battery, formed by an outer frame made of hollow profiles and a base. In the mounting position for mounting at least one battery, the tray's opening faces upwards, whereas in the installed position in the electric vehicle, the opening faces downwards. The opening can be closed with a cover. A layer with a convex and / or honeycomb structure is arranged on or against the cover, serving in particular as underride protection. This layer with the convex and / or honeycomb structure can be made of a metallic material or a fiber-reinforced plastic. From DE 10 2016 102 181 A1, it is known to fill a conventionally available crumple zone between the vehicle body and a battery housing by means of an additional enclosure (shock-absorbing component) in such a way that an impact applied to said enclosure is dampened. The enclosure comprises several side walls arranged around and attached to the battery, each containing several arcuate outer wall segments and a flat inner wall that defines several enclosed semi-cylindrical pockets. The respective arcuate outer wall and the flat inner wall are formed in an extrusion process. From US 2017 / 0 162 923 A1, a battery module with a battery housing is known, the outer wall of which has a plurality of longitudinal reinforcing ribs projecting outwards from the housing. From WO 2019 / 028 569 A1, a battery with a battery housing is known that has a closed cavity structure for accommodating cylindrical battery cells. The battery housing also has rounded corners for better retention of said battery cells, which are connected to each other by largely flat wall sections. In the lower or bottom area of ​​the battery housing, the rounded corners are each supplemented by a so-called retaining cavity. A mounting groove for securing the battery is formed between the retaining cavities. From the applicant's patent application DE 10 2017 202 354 A1, which is closest to the subject matter of the application, a battery assembly is further known, comprising a battery housing for receiving at least one cell pack with at least one battery cell. This battery housing is formed by a hollow profile strand. At least one housing cover element for closing the hollow profile strand is assigned to each end of the hollow profile strand. The hollow profile strand can be formed by an extruded profile or a pultruded profile, also referred to as a pultruded profile, wherein the extruded profile is preferably made of a metal and the pultruded profile is preferably made of a plastic or a composite material, such as a fiber-reinforced plastic.Such a battery housing advantageously combines features of a support component, a system protection space, a crash structure, a temperature control body and a cell frame to absorb internal and external forces acting on the battery housing. Apart from that, a battery device for bicycles is also known from CN 2 06 327 505 U, which is designed as a concealed or hidden battery device. The object of the invention, particularly with regard to the prior art described above (DE 10 2017 202 354 A1), is to create a further improved vehicle battery with a battery housing, while retaining its advantages. This battery housing is preferably able to withstand external forces acting upon it, resulting, for example, from contact between the battery housing and the ground (road surface) or from any other crash event. Furthermore, it is an object of the invention to provide a motor vehicle equipped with such a vehicle battery. Starting from a vehicle battery for a motor vehicle, in particular an electrically powered motor vehicle, with a battery housing in which at least one cell pack with at least one battery cell is arranged, wherein the battery housing is formed by a hollow profile strand, the stated problem is solved by the fact that the battery housing designed as a hollow profile strand has four wall sections extending over the entire length of the hollow profile strand and curved outwards towards the housing with a bridge-arch-like profile when viewed in cross-section of the hollow profile strand, wherein the curvature of the wall sections is homogeneous over the entire length of the hollow profile strand. The wall sections, which are curved outwards or convexly along the entire length of the battery housing designed as a hollow profile strand, advantageously increase the stiffness and strength of the battery housing and, consequently, of the vehicle battery in general, with minimal effort, so that battery cells arranged inside the battery housing enjoy increased protection against forces acting on the battery housing from the outside, which result, for example, from the vehicle battery hitting an obstacle. The dependent claims describe preferred further developments or embodiments of the invention. It is preferably provided that at least one curved wall section of the vehicle battery, when installed inside the vehicle, points downwards towards the road surface. This allows the curvature to simultaneously act as underride protection for the vehicle, thus eliminating the need for a separate or additional underride guard, as favored by the prior art (DE 10 2016 115 647 B3). Potential impact forces against the vehicle battery from below, which could occur if the vehicle were to bottom out on the road surface, are transferred by means of the curved wall section, similar to a bridge arch, into at least one side wall of the battery housing, which is designed as a hollow profile. This significantly increases profile stability and further optimizes cell protection. In a further development of the invention, it is also provided that the battery housing, designed as a hollow profile strand, has at least one wall section extending over the entire length of the hollow profile strand and curved outwards towards the housing. When the vehicle battery is installed inside the vehicle, this wall section points in a direction other than downwards towards the vehicle's road surface. If, for example, the wall section points towards a side of the vehicle, increased protection of the battery components, particularly battery cells, arranged in the battery housing is achieved in the event of a side-impact collision. To further increase the stiffness and strength of the battery housing, the housing, designed as a hollow profile strand, is provided with at least one intermediate floor formed integrally with the strand and extending longitudinally along the hollow profile strand. This creates at least two separate compartments running lengthwise within the hollow profile strand, one of which serves to accommodate the at least one cell pack. The other compartment running lengthwise along the hollow profile strand allows for the simple and cost-effective integration of a cooling device into the battery housing by acting as a flow channel for a cooling fluid. Furthermore, this compartment can also serve to route cables and / or lines, including media lines. In a further development of the invention, it is provided that the hollow profile strand has at least one web element extending along the hollow profile strand and formed integrally with it. This advantageously reinforces the battery housing and also opens up the possibility of using profile strands with large profile widths. Such profile strands allow the battery housing's receiving spaces for battery cells or cell packs to be separated from one another, with the advantage that, for example, in the event of a defect in one of the battery cells or a cell pack, increased protection is provided for battery cells or cell packs arranged in adjacent receiving spaces. Preferably, the battery housing, designed as a hollow profile strand, has a square or rectangular cross-section, which advantageously corresponds to predominantly cuboid-shaped battery cells and cell packs formed therefrom with high volumetric energy density. Preferably, the hollow profile strand is advantageously formed by an extruded profile or a pultruded profile, also known as a pultruded profile. The extruded profile preferably consists of a metal, such as aluminum, whereas the pultruded profile is preferably made of a plastic or a composite material. This advantageously minimizes the component and assembly scope, as well as system costs, since such profile strands are particularly cost-effective to manufacture, maximize volumetric energy density, allow for easy replacement of individual battery cells or an entire cell pack, offer high system flexibility, and also ensure a high level of system safety.The curved shape of the relevant wall sections of the hollow profile strand, extending over the entire length of the hollow profile strand, can be reproduced particularly easily and cost-effectively by means of an extrusion or pultrusion profile. As the invention further provides, at least one housing cover element is assigned to each end of the battery housing designed as a hollow profile strand, whereby the receiving spaces for the electrical components of the vehicle battery, in particular battery cells, can be sealed in a fluid-tight manner. The invention also relates to a motor vehicle, in particular an electrically powered motor vehicle, with a vehicle battery of the type described above. The invention is explained in more detail below with reference to an embodiment schematically illustrated in the drawings. However, it is not limited to this embodiment but encompasses all embodiments defined by the claims. For the purposes of this description, the usual direction of travel of a motor vehicle shall be designated by “-x” (“minus x”), the direction opposite to its usual direction of travel by “+x” (“plus x”), starting from the usual direction of travel (-x), the horizontal direction perpendicular to the x-direction to the right by “+y”, starting from the usual direction of travel (-x), the horizontal direction perpendicular to the x-direction to the left by “-y”, the vertical direction perpendicular to the x-direction upwards by “+z”, and the vertical direction perpendicular to the x-direction downwards by “-z”.This method of designating spatial directions in Cartesian coordinates corresponds to the coordinate system generally used in the automotive industry. Furthermore, terms such as "front," "rear," "top," "bottom," and terms with similar meanings, including "right" and "left," are used in the manner commonly employed to indicate direction on a motor vehicle. Figure 1 shows, in a highly schematic way, a vehicle equipped with a vehicle battery designed according to the invention; Figure 2 shows a perspective view of a cell pack composed of several battery cells for use in said vehicle battery, the battery cells of which are electrically interconnected; Figure 3 shows the cell pack according to Figure 2, supplemented by insulation surrounding the battery cells and two guide profiles arranged laterally; Figure 4 shows the cell pack according to Figure 5.3 at the time of its assembly into a battery housing according to the prior art, Fig. 5 a perspective front view of the battery housing equipped with a cell pack according to Fig. 4, and Fig. 6 a perspective close-up view of a battery housing with a further development essential to the invention, wherein the battery housing is designed to accommodate, by way of example, two cell packs. Fig. 1 shows a motor vehicle 1 with an electric motor 2 as the drive motor and a vehicle battery 3 forming a traction battery, in particular a high-voltage battery. According to this embodiment, the motor vehicle 1 is therefore purely electrically powered. The vehicle battery 3 is arranged in the underbody area of ​​the motor vehicle 1. The invention also covers, of course, a so-called hybrid vehicle, which, in addition to one or more electric motors 2, also has an internal combustion engine, or any other vehicle 1 which has or can have a vehicle battery 3 of the type described below (not shown in the drawing). The vehicle battery 3 has at least one cell pack 4, shown in detail in Fig. 2, which is composed of a plurality of battery cells 5, in this case seventy-two battery cells 5. The battery cells 5 are electrically interconnected and form both a high-voltage and a low-voltage interface 6, 7. In addition, the interconnected battery cells 5 are surrounded by insulation 8, preferably made of a plastic (see Fig. 3). According to this embodiment, the battery cells 5 are cuboid in shape and combined to form an elongated, also cuboid, cell pack 4. This results in a high volumetric energy density for the cell pack 4. In this embodiment, a guide profile 9 is assigned to each side of the cell pack 4 in its longitudinal direction and is connected to it by a form-fit, force-fit, and / or material-fit connection, for example, by adhesive bonding (Fig. 3). These guide profiles 9 increase the stability of the cell pack 4 and facilitate its assembly into a prepared battery housing 10. The battery housing 10 is formed by a hollow profile strand 11, which can be cut to any length depending on the current energy requirement and the available installation space, and according to this embodiment has an inner contour that is largely complementary to the outer contour of the cell pack 4, in particular a rectangular hollow profile cross-section (Figs. 4 and 5). A housing cover element 12, 13 is assigned to each end of said hollow profile strand 11 (see Fig. 5). According to this exemplary embodiment, the battery housing 10 extends in the longitudinal direction (X-direction) of the vehicle. Of course, the battery housing 10 or the hollow profile section 11 can assume any orientation within the vehicle 1, so the invention is not limited to the aforementioned longitudinal direction (X-direction). However, the orientation in the longitudinal direction (X-direction) of the vehicle is preferred, as this ensures a high level of crash safety for the battery housing 10, which accommodates the cell pack 4, in the event of a frontal collision. The hollow profile strand 11 is formed by a simple and cost-effective extrusion profile or a pultruded profile. The former is preferably used for the production of metal battery housings 10, such as battery housings 10 made of aluminum or an aluminum alloy, whereas the latter is preferably used for the production of a battery housing 10 made of a plastic or a composite material, in particular a fiber-reinforced plastic. As can be seen in Figures 4 and 5, a battery housing 10 is shown here which accommodates a single cell pack 4 of the type described above. In practice, however, depending on the current energy requirements and the available installation space of the respective application, it may be necessary to use and connect two or more such cell packs 4.These cell packs 4 can each be arranged in a battery housing 10 or in a common battery housing 10. Fig. 6 shows a battery housing 10 designed, by way of example, to accommodate two cell packs 4 arranged axially side by side in the transverse direction (Y-direction) of the vehicle. However, the invention is not limited to the number and arrangement of cell packs 4 described above in a common battery housing 10, but encompasses any possible number and arrangement of the cell packs 4 relative to each other. For example, two or more cell packs 4 can also be arranged one above the other in the vertical direction (Z-direction) of the vehicle. Any combination of said arrangements of the cell packs 4, namely axially parallel side by side and one above the other, as well as axially one behind the other, is of course also covered by the invention (not shown in the drawing). According to this embodiment, the cell packs 4 are separated from one another by means of a web element 14, which is formed integrally with the battery housing 10 (which is formed by a hollow profile section 11) and extends longitudinally along the hollow profile section 11. This means that two separate receiving spaces 15a and 15b are created, each for receiving one cell pack 4. In this embodiment, complete separation of the aforementioned receiving spaces 15a and 15b is achieved by extending the web element 14 over the entire length and height of the hollow profile section 11. This provides further reinforcement to the battery housing 10. Furthermore, it facilitates easier handling of the cell packs 4, for example, when installing them in the battery housing 10, and offers a degree of protection to adjacent cell packs 4 or battery cells 5 in the event of a defect in one of the cell packs 4 or a single battery cell 5.Alternatively, web elements 14 can also be provided which extend only partially in length and / or height of the hollow profile string 11 (not shown in the drawing). As can be seen further in Fig. 6, the battery housing 10, designed as a hollow profile 11, now has, in contrast to the prior art, wall sections 16a to 16d that are convexly curved outwards. The curved wall sections 16a to 16d extend over the entire length of the hollow profile 11 or battery housing 10, with the respective curvature 17 of the wall sections 16a to 16d being homogeneous over the entire length of the hollow profile 11. Viewed in cross-section, the wall sections 16a to 16d that are convexly curved outwards therefore have a bridge-arch-like shape. As shown in Fig. 6, the wall sections 16a to 16d are curved and, when the vehicle battery 3 is installed inside the vehicle 1, point downwards (16a, 16b) towards a platform 18 (see Figs. 1 and 6) of the vehicle 1 and laterally (16c, 16d) towards the side of the vehicle 1. The wall sections 16a, 16b pointing downwards towards the platform 18 extend below one of the formed receiving spaces 15a, 15b of the battery housing 10. In the area of ​​the web element 14, they connect to each other and to the web element 14. On the other side, the wall sections 16a, 16b each connect to a wall section 16c, 16d that serves as a side wall of the battery housing 10. In the event of an impact on the vehicle battery 3 located in the underbody area of ​​the vehicle 1, or its battery housing 10, resulting, for example, from the vehicle 1 bottoming out on the road surface 18, said impact is advantageously transferred into the web element 14 and into at least one wall section 16c, 16d, which functions as a side wall, by means of the bridge-arch-like shape of the wall sections 16a, 16b pointing downwards towards the road surface 18. This increases the profile stability and significantly enhances cell protection. As regards the curved wall sections 16c, 16d facing the side of the vehicle, these have a particularly advantageous effect in the event of a side-impact collision according to this embodiment. A resulting force impulse is advantageously introduced into at least one of the wall sections 16a, 16b facing downwards towards the roadway 18 and into a wall section 19 facing upwards of the battery housing 10, which is designed as a hollow profile 11. The aforementioned wall section 19, pointing upwards towards the vehicle, is designed to be flat according to this embodiment. Alternatively, and thus also covered by the invention, it can also be designed in accordance with the wall sections 16a, 16b, which point downwards towards the track 18, resulting in even greater stiffening of the hollow profile 11. In this case, the resulting upper wall sections are then curved upwards towards the vehicle (not shown in the drawing). As can be seen in Fig. 6, an intermediate floor 20 is arranged within each of the formed receiving spaces 15a, 15b. The intermediate floor 20 is formed integrally with the hollow profile section 11 and also extends longitudinally along the hollow profile section 11. According to this embodiment, the respective intermediate floor 20 limits the curvature 17 of the respective wall section 16a, 16b, which points downwards towards the roadway 18, or its bridge-like course, thereby advantageously forming a narrow space 21 extending along the hollow profile section 11. This space 21 can advantageously serve for media routing, in particular as a flow channel for a cooling fluid. The intermediate floor 20 thus functions as a support or storage platform for the respective cell pack 4 and enables heat exchange between the battery cells 5 of the respective cell pack 4 and the cooling fluid.Furthermore, this space can also be used for routing cables and / or lines, including media lines. The battery housing 10 of the vehicle battery 3, described with reference to Fig. 6 and further developed according to the invention, specifically comprises two cell packs 4 arranged or capable of being arranged parallel to each other in separate receiving spaces 15a, 15b of the same. However, the invention is not limited to this specific embodiment of the battery housing 10, but also encompasses, as already explained above, a battery housing 10 designed with at least one curved wall section 16a to 16d, in which only one cell pack 4 is arranged or more than two cell packs 4 are arranged, the latter being arranged parallel to each other and / or one above the other and / or axially one behind the other (not shown in the drawing). Even with more than two cell packs 4 arranged parallel to each other, intermediate shelves 20 are preferably provided, in particular for supporting the respective cell pack 4.For the upper cell packages 4 of a cell package stack, at least two interconnected intermediate floors 20, arranged one above the other at a distance from each other and extending along the hollow profile section 11 (not shown in the drawing), can be provided to create a flow channel (chamber 21) for a cooling fluid. Furthermore, even if more than two axially parallel cell packages 4 are arranged side by side, they can be separated from each other by means of web element(s) 14. Reference symbol list 1 Motor vehicle 2 Electric motor 3 Vehicle battery 4 Cell pack 5 Battery cell 6 High-voltage interface 7 Low-voltage interface 8 Insulation 9 Guide profile 10 Battery housing 11 Hollow profile string 12 Housing cover element 13 Housing cover element 14 Web element 15a,b Receiving spaces 16a-d Wall sections 17 Curvature 18 Driving platform 19 Wall section 20 Intermediate floor 21 Space

Claims

Vehicle battery (3) for a motor vehicle (1), in particular an electrically powered motor vehicle (1), with a battery housing (10) in which at least one cell pack (4) with at least one battery cell (5) is arranged, wherein the battery housing (10) is formed by a hollow profile strand (11), characterized in that the battery housing (10) designed as a hollow profile strand (11) has four wall sections (16a-d) extending over the entire length of the hollow profile strand (11) and curved outwards towards the housing, with a bridge-arch-like profile seen in the cross-section of the hollow profile strand (11), wherein the curvature (17) of the wall sections (16a-d) is homogeneously formed over the entire length of the hollow profile strand (11). Vehicle battery (3) according to claim 1, characterized in that two of the four curved wall sections (16a, 16b) in the vehicle battery (3) installed inside the motor vehicle (1) point downwards towards a roadway (18) of the motor vehicle (1). Vehicle battery (3) according to one of the preceding claims, characterized in that two of the four curved wall sections (16c, 16d) in the vehicle battery (3) installed inside the motor vehicle (1) point towards the side of the motor vehicle (1). Vehicle battery (3) according to one of the preceding claims, characterized in that the battery housing (10) designed as a hollow profile strand (11) has at least one intermediate floor (20) formed integrally with it and extending in the longitudinal direction of the hollow profile strand (11). Vehicle battery (3) according to one of the preceding claims, characterized in that the battery housing (10) designed as a hollow profile strand (11) has at least one web element (14) formed integrally with it and extending in the longitudinal direction of the hollow profile strand (11). Vehicle battery (3) according to one of the preceding claims, characterized in that the hollow profile strand (11) is formed by an extruded profile or a pultruded profile. Vehicle battery (3) according to one of the preceding claims, characterized in that at least one housing cover element (12, 13) is assigned to each end of the battery housing (10) designed as a hollow profile strand (11). Motor vehicle (1), in particular an electrically powered motor vehicle (1), with a vehicle battery (3) according to one of the preceding claims.

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