Frame for a battery box

Abstract

Frame (100) for a battery box for a motor vehicle, having the following features: - at least one first stiffening structure (110) and at least one second stiffening structure (120) adjacent to the first stiffening structure (110) and one receiving structure (130) adjacent to the second stiffening structure (120); - the receiving structure (130) is designed to receive a battery; - the receiving structure (130) is delimited by the first stiffening structure (110) and the second stiffening structure (120) from at least two sides, the two sides being opposite one another, thereby delimiting a volume; - the first stiffening structure (110) has a higher stiffness and a higher strength than the second stiffening structure (120); - the second stiffening structure (120) is designed to collapse when a threshold value is exceeded, characterized in - that the second stiffening structure (120) is constructed from at least two chambers (123), wherein - the chambers (123) of the second stiffening structure (120) and / or the second stiffening structure (120) are made of plastic - and / or that the chambers (123) of the second stiffening structure (120) and / or the second stiffening structure (120) are made of deformable materials, foams and / or elastomers.

Description

[0001] The invention relates to a frame for a battery box for a motor vehicle according to the preamble of claim 1.

[0002] Today's battery boxes must be mechanically highly rigid and strong to protect the internal cells. This is typically achieved by a rigid and strong surrounding frame made of metal, e.g., extruded aluminum profiles, or plastic, with or without continuous fiber inserts. The operating principle is designed to ensure minimal deflection or deformation of the frame within the battery box. The aim is to exert as little force as possible on the internal battery cells.

[0003] If a battery cell in an electric car is damaged, this can have various consequences and, in the worst case, result in a vehicle fire.

[0004] To prevent such scenarios, battery boxes are constructed as robustly as possible and have various mechanisms to avoid stress on the battery cell in the event of a crash.

[0005] To remedy this problem, the generic document DE 10 2020 112 794 A1 discloses a battery housing for a vehicle battery. The housing comprises a stiffening structure extending in the transverse direction of the battery housing and a receiving space for accommodating at least one cell module. The stiffening structure comprises an outer cross strut and an inner cross strut. The cross struts are arranged in the longitudinal direction of the battery housing between a housing end face and the receiving space closest to this housing end face and are spaced from one another in the longitudinal direction by a deformation space. The spacing is designed such that the outer cross strut can deform under impact without stressing the inner cross strut.This is achieved by the outer cross strut having a greater bending stiffness against mechanical loads acting in the longitudinal direction of the battery housing than the inner cross strut.

[0006] EP 3 053 207 B1 discloses the use of an additional escape zone within the battery module interior. One or more battery cells can escape into this escape zone when subjected to external force. This allows the maximum force acting on individual battery cells to be reduced, thus reducing the risk of severe damage to the battery cells.

[0007] DE 10 2016 115 611 B3 discloses a battery carrier for an electric motor vehicle, which is arranged in an underfloor area of ​​an electric motor vehicle, wherein the battery carrier has a tray and a lid and is characterized in that the tray is formed from an outer peripheral frame and a base coupled to the frame, wherein an opening is formed on the side opposite the base and the opening is closed by a lid and that the frame is formed from a hollow profile.

[0008] DE 10 2018 120 268 A1 discloses a battery box for a motor vehicle for accommodating battery cells, comprising a structural frame with at least two structural components joined to one another at their ends. Each structural component has at least one partially hollow profile segment with a substantially L-shaped cross-section. A reinforcing element for absorbing impact energy in the event of an impact is arranged within at least one of the profile segments. The reinforcing element is a molded part with a plurality of open cells that are adjacent to one another and arranged with their longitudinal extension substantially parallel to one another. When the battery box is mounted in the motor vehicle, the open cells are aligned with their longitudinal extension substantially parallel to the transverse direction of the vehicle.

[0009] EP 2 976 797 B1 discloses a storage cell assembly for a motor vehicle with an electric drive, which has a housing in which storage cells are arranged, and a motor vehicle with such a storage cell assembly.

[0010] DE 10 2020 129 005 A1 discloses a battery assembly for a motor vehicle, wherein the battery assembly comprises at least a first battery cell with a cell housing and a carrier on which the first battery cell is arranged. At least the first battery cell is displaceable relative to the carrier when subjected to a predetermined minimum force. Furthermore, the invention also relates to a motor vehicle with such a battery assembly.

[0011] US 2011 / 0 143 179 A1 discloses a resin-molded battery rack having a bottom wall on which batteries are mounted, a circumferential side wall surrounding the perimeter of the bottom wall, and a battery cover covering the battery rack. A flange is provided on the upper surface of the circumferential side wall; and a metallic case-shaped frame is attached adjacent to the outer wall of the battery rack. The flange and the battery cover are fixed to the upper surface of the metallic case-shaped frame by fasteners.

[0012] DE 10 2022 104 178 A1 discloses a drive battery for a motor vehicle, comprising a drive battery housing having a bottom wall and a cover wall, a battery cell layer arranged between the bottom wall and the cover wall and comprising a plurality of battery cells, and a battery cell contact system. A support layer, which can also be called a deformation layer or spacer layer depending on its function, is arranged between the battery cell layer and the bottom wall to protect the battery cell layer in the event of a collision with the bottom wall. The support layer is designed as a carrier for the battery cell contact system.

[0013] DE 10 2019 207 512 B4 discloses a vehicle with a high-voltage battery, with at least one battery module, in the module housing of which a plurality of cylindrical round battery cells are arranged with mutually parallel round cell longitudinal axes lying in the vehicle's horizontal planes, wherein the round battery cells arranged in the battery module are in line contact with one another in a loose stack, wherein the round battery cells are aligned with their round cell longitudinal axes in alignment with the vehicle's transverse direction and, in the event of a side crash, the round battery cells are integrated in a transverse load path via which the side crash force can be transmitted to a side of the vehicle facing away from the crash.

[0014] It is therefore an object of the invention to provide a device which further develops the state of the art.

[0015] The problem is solved by the features of claim 1. Advantageous embodiments can be found in the subclaims and the description.

[0016] One subject of the invention is a frame for a battery box for a motor vehicle having the following features: - at least one first stiffening structure and at least one second stiffening structure adjacent to the first stiffening structure and a receiving structure adjacent to the second stiffening structure; - the receiving structure is designed to receive a battery; - the receiving structure is delimited by the first stiffening structure and the second stiffening structure from at least two sides, the two sides being opposite each other, thereby delimiting a volume or a spatial area; - the second stiffening structure is arranged between the first stiffening structure and the receiving structure; - the first stiffening structure has a higher stiffness and a higher strength than the second stiffening structure; - the second stiffening structure is designed to collapse when a threshold value is exceeded.

[0017] The receiving structure for the battery is formed by the distance between the stiffening structures adjacent to the receiving structure on both sides. The receiving structure is designed to receive a battery and can for this purpose comprise fastening means such as fastening bolts and / or cooling connections. Space for electronics, such as a battery management system, can also be provided in the receiving structure. In an advantageous embodiment, the stiffening structures can each run parallel to the driver or passenger door in the X direction. To enclose the volume, a stiffening structure running in the Y direction is not necessary, but can be provided since the motor vehicle only has a finite extent. The first stiffening structure and the second stiffening structure each have a height.This means that the first stiffening structure and the second stiffening structure each span a volume with their respective outer contours.

[0018] A motor vehicle according to the invention is a motorized vehicle used to transport people or goods on roads. It may have a body, an engine, wheels, and other components necessary for the operation and safety of the vehicle. Motor vehicles can have various types of propulsion, such as gasoline, diesel, electric, or hybrid engines. Motor vehicles include, in particular, cars, buses, and trucks.

[0019] According to the invention, the second stiffening structure is constructed from at least two chambers. A chamber is a closed structure extending in a plane. The structure can consist of the material from which the second stiffening structure is made. The chambers can be formed by inserting ribs into the second stiffening structure. The chambers can be open or closed at the top and bottom, or a combination of open and closed. The chambers can also be closed with a lid that arches over the receiving structure. If the second stiffening structure is made of foams and / or elastomers, or the chambers of the second stiffening structure are filled with foams and / or elastomers, these can be formed as solid material or with a recess for setting specific threshold values. In an advantageous embodiment, the chambers can run parallel to the battery and adjoin one another.The chambers can be designed so that the respective chambers collapse at different threshold values. This means that, for example, two adjacent chambers and / or distributed chambers of the second stiffening structure have different threshold values ​​and therefore collapse under different force application. Several adjacent chambers of the second stiffening structure can also have the same threshold value, with adjacent chambers with a higher or lower threshold value. In the event of a collision, not all chambers collapse simultaneously under the same force application, but rather earlier or later depending on their threshold value. This means that in the event of a collision, the deformation of the first stiffening structure can be controlled by the collapse of the second stiffening structure and thus the load on the battery.

[0020] A battery or battery pack can consist of several cells connected to one another. The cells can be arranged in modules to increase the total capacity of the battery. These modules can in turn be combined into a battery pack that can be installed in the motor vehicle, particularly in the supporting structure.

[0021] The collapse of the second stiffening structure refers to the condition in which the second stiffening structure or individual chambers of the second stiffening structure lose(s) their load-bearing capacity and the stiffening structure collapses or is compressed. When a structure collapses, it loses its stability and can no longer fulfill its intended function. Collapse of the second stiffening structure or its chambers is referred to in particular when the second stiffening structure is compressed by more than 20 percent of the original distance between the first stiffening structure and the receiving structure or a thickness of the second stiffening structure between the first stiffening structure and the receiving structure in which the battery is arranged, due to the action of a force on the stiffening structures, e.g. due to an accident.The original distance is the distance between the first stiffening structure and the receiving structure or the thickness of the second stiffening structure in the delivery state, ie without an accident or without the application of force.

[0022] The collapse of the second stiffening structure upon reaching or exceeding a predefined threshold is intended within the scope of the invention. This allows the maximum load on the battery to be predetermined. The threshold in the context of mechanical stress refers to the different levels or intensities of stress to which a material or stiffening structure is exposed. These thresholds can vary depending on the application and are measured using factors such as pressure, tensile force, bending moment, or shear stress. Knowing the thresholds is important to ensure that a material or structure can withstand the requirements and that premature fatigue or failure does not occur. The collapse of the second stiffening structure enables a defined failure of the cells directly adjacent to the battery.This creates more deformation space for the first stiffening structure. This stiffens in the event of a side impact, for example, and, if the second stiffening structure were missing, would exert direct force on the battery, as it acts as an abutment. Due to the presence of the second stiffening structure and its collapse, the force of an impact cannot build up any further, and the first stiffening structure, as well as the collapsed second stiffening structure, can continue to bend. This allows the impact energy to be dissipated without the battery, which is located in the support structure, being subjected to excessive forces locally. In an advantageous embodiment, the second stiffening structure can be designed such that it only collapses locally, namely in the area of ​​the highest impact force. The structure adjacent to it on the side, ieThe intact chambers of the second stiffening structure do not collapse but continue to contribute to stiffness during the impact.

[0023] The stiffness of the first or second stiffening structure refers to its ability to deform under load. It is a measure of how well the stiffening structure, or the chambers, ribs, or struts it contains, can retain its shape when subjected to external forces. A stiff stiffening structure has a high stiffness and tends to deform only slightly, whereas a less stiff stiffening structure tends to deform more easily. Stiffness can depend on both the elasticity of the stiffening structure material and the geometry of the stiffening structure, such as the shape and size of the cross-sectional area of ​​a stiffening structure and / or the use of ribs and / or struts, as well as the introduction of buckling and / or predetermined breaking points.

[0024] Strength is also a material property of the first or second stiffening structure and describes the mechanical resistance a material offers to plastic deformation or separation. Strength is a measure of the stress a material can withstand and thus represents a value that can be easily determined from the data sheet of the corresponding material (e.g., tensile strength).

[0025] In a preferred embodiment, the first stiffening structure of the frame can have a different geometry than the second stiffening structure of the frame. This means that the first stiffening structure can vary in width and height compared to the second stiffening structure. The first and / or second stiffening structures can also be designed in a stepped manner.

[0026] According to the invention, the chambers of the second stiffening structure and / or the second stiffening structure are made of plastic, in particular by compression or injection molding. Alternatively or additionally, the chambers and / or the second stiffening structure can be made of deformable materials, in particular foams and / or elastomers. Additionally or alternatively, the first stiffening structure and / or the second stiffening structure can be made of extruded profiles or welded sheets. In an advantageous embodiment, a combination of metal and plastic can also be provided. These material connections can be created by gluing.

[0027] In a further preferred embodiment, the foams and / or elastomers can be arranged flatly and / or locally on the region facing the battery. This means that the foams and / or elastomers are arranged flatly and / or locally between the first stiffening structure and the receiving structure. If the second stiffening structure is formed from foams and / or elastomers, it can also be arranged flatly and / or locally between the first stiffening structure and the receiving structure. The second stiffening structure can also be distributed if it is constructed from sheet metal and / or extruded profiles and / or from a mixture of different materials. The first stiffening structure can also be formed flatly and / or locally congruent with the second stiffening structure.

[0028] In a preferred embodiment, the chambers of the second stiffening structure and / or the second stiffening structure, which in particular consist of or comprise plastic, can have local ribs, wherein the local ribs include predetermined breaking points. Additionally or alternatively, the local ribs can be configured with kinks.

[0029] Ribs are defined as the crossbars present in the chambers of the second stiffening structure. The crossbars can extend at right angles from a side wall of the chamber or enclose an angle. The chambers can also be created by inserting the crossbars. The crossbars can be created during production using compression or injection molding, or they can be added subsequently.

[0030] In a further preferred embodiment, the local ribs may have a reduced cross-section and / or a curved S-shape.

[0031] The ribs can serve both to stabilize the chambers and to allow them to collapse in a controlled manner. For this purpose, the ribs can be designed so that the material thickness is reduced at a specific location or along a specific path, which is commonly referred to as a predetermined breaking point. Alternatively, the ribs can have a kink, which also creates a predetermined breaking point. A kink is, in particular, a sudden change in the direction of an imaginary line through the rib. This ensures that the second stiffening structure fails at this point when a corresponding force above a threshold is applied, causing the second stiffening structure to collapse. Foams and / or elastomers are deformed accordingly.

[0032] In a preferred embodiment, the first stiffening structure and the second stiffening structure can run parallel to the battery and / or the receiving structure and can be axially symmetrical to the X-axis when the battery is inserted into the frame. The length of the individual parallel sides can vary. Alternatively, the battery and / or the receiving structure can be completely enclosed by the first stiffening structure and the second stiffening structure. "Enclosed" means that the first stiffening structure and the second stiffening structure can be configured to extend circumferentially around the battery and / or the receiving structure in an XY plane.

[0033] In a further preferred embodiment, the first and / or second stiffening structure can be divided into several subregions parallel to the battery and / or the support structure. The chambers of the second stiffening structure can be spaced apart from one another. The chambers of the second stiffening structure can be designed with different geometries so that they collapse at different threshold values. This creates several degrees of freedom. This means that various deformations can be specifically planned in advance when designing accident scenarios. The first stiffening structure can also be designed with predetermined breaking points and / or kinks for this purpose. This allows the design to accommodate locally required deformation behavior.

[0034] The individual axes and planes, as well as the rotational and swivel movements, are referenced to the vehicle coordinate system commonly used in automotive engineering. The origin of the coordinate system is at the vehicle's center of gravity. The positive X-axis points in the direction of travel. The positive Z-axis points upwards, toward the vehicle roof. The positive Y-axis is perpendicular to the driver's door of a left-hand drive vehicle and points to the left in the direction of travel. Not only directional movements but also moments can occur on the vehicle. The moments occur around the coordinate axes.

[0035] Movement around the X-axis is called roll, movement around the Y-axis is called pitch, and movement around the Z-axis is called yaw. Yaw can also be described as "skidding."

[0036] In a preferred embodiment, the frame is designed as a sandwich construction. The first stiffening structure, the second stiffening structure, the support structure, the second stiffening structure, and then the first stiffening structure are arranged in an XY plane, viewed from the side (i.e., from the Y direction of the motor vehicle). This is intended to protect the battery in the event of a side impact. Additionally or alternatively, the frame can also completely enclose the battery.

[0037] The first stiffening structure is positioned closer to the driver's or passenger door than the second stiffening structure. The receiving structure with the battery is adjacent to the second stiffening structure. The receiving structure of the frame can have a larger volume and / or surface area than the second and first stiffening structures to accommodate the battery.

[0038] In a further preferred embodiment, the first stiffening structure can be constructed from several chambers.

[0039] In a preferred embodiment, some, but not all, of the chambers of the first stiffening structure can be reinforced, wherein the reinforced chambers can be arranged parallel to the second stiffening structure. This allows a portion of the first stiffening structure to be reinforced. For this purpose, struts can be formed in the chambers of the first stiffening structure. This serves to stiffen the frame. The first stiffening structure can thus bend toward the second stiffening structure in the event of an impact without failing.

[0040] The term "without failure" should be understood by those skilled in the art within realistic mechanical limits. If a limiting load or a certain force level is exceeded, the first stiffening structure will also collapse or fail. The force level is to be understood as a threshold value. If this limit is exceeded, the corresponding stiffening structure may fail or collapse. The threshold value depends on the material and geometry. However, failure or collapse of the second stiffening structure, or at least parts of it, should occur before the failure or collapse of the first stiffening structure.

[0041] The invention is described below purely by way of example with reference to the drawings. They show: Fig. 1 shows a schematic structure of an embodiment of a frame according to the invention with a receiving structure; Fig. 2 shows a schematic structure of an embodiment of a frame according to the invention with tapered ribs as a predetermined breaking point; Fig. 3 a schematic structure of an embodiment of a frame according to the invention with kinks as predetermined breaking points; and Fig. 4 a schematic structure of a battery box with an embodiment of a frame according to the invention with distributed first and second regions.

[0042] Fig. 1 shows a frame 100 for a battery box, wherein the frame 100 comprises a first stiffening structure 110, a second stiffening structure 120, and a receiving structure 130. The first stiffening structure 110 is stepped in the illustrated embodiment. The second stiffening structure 120 is arranged between the first stiffening structure 110 and the receiving structure 130. The receiving structure 130 serves to accommodate a battery. The second stiffening structure 120 and the first stiffening structure 110 continue symmetrically on the opposite side of the receiving structure 130. The arrow 140 shows a schematic lateral force introduction, which bends the first stiffening structure 110 and collapses the second stiffening structure 120 in order to create more space for the first stiffening structure 110 and thereby protect the receiving structure 130 or the battery contained therein.

[0043] Fig. Figure 2 shows a schematic structure of the first stiffening structure 110 and the adjacent second stiffening structure 120 of the frame 100 for a battery box. The second stiffening structure 120 is designed as a variant with ribs with a predetermined breaking point 121. The predetermined breaking point is formed by a tapering of the ribs 121. The chambers 123 of the second stiffening structure 120 are formed or subdivided by the ribs 121 with a predetermined breaking point. The first stiffening structure 110 is equipped with chambers 112 in one part and with additional struts 111 in a second part.

[0044] Fig. Figure 3 shows a schematic structure of the first stiffening structure 110 and the second stiffening structure 120 of a frame 100 for a battery box. The second stiffening structure 120 is designed as a variant with ribs with kinks 122. The kinks 122 can have the same thickness or an alternating thickness along their length. The chambers 123 are formed by the ribs with kinks 122. The first stiffening structure 110 is equipped with chambers 112 in a first part and with additional struts 111 in the chambers 112 in a second part.

[0045] Fig.4 shows a schematic structure of a battery box with a frame 100 with a first circumferential stiffening structure 110 and a second distributed stiffening structure 120. The second stiffening structure is arranged where space may be required in the collision design. This allows the design to accommodate locally required deformation behavior. The first stiffening structure 110 is shown as a circumferential frame. The second stiffening structure 120 is formed by distributed squares 120 that run parallel to the long side of the receiving structure 130 or the first stiffening structure 110. The squares of the second stiffening structures 120 are of different sizes, which allows for the different magnitude of the forces exerted in an accident to be accommodated.A battery can be accommodated in the receiving structure 130 and is enclosed by the first stiffening structure 110 and borders the squares of the second stiffening structure 120. List of reference symbols 100 frames 110 First stiffening structure 111 Bracing 112 Chamber 120 Second stiffening structure 121 ribs with predetermined breaking point 122 ribs with kinks 123 Chamber 130 Recording structure 140 Lateral force introduction

Claims

[1] Frame (100) for a battery box for a motor vehicle, having the following features: - at least one first stiffening structure (110) and at least one second stiffening structure (120) adjacent to the first stiffening structure (110) and one receiving structure (130) adjacent to the second stiffening structure (120); - the receiving structure (130) is designed to receive a battery; - the receiving structure (130) is delimited by the first stiffening structure (110) and the second stiffening structure (120) from at least two sides, the two sides being opposite one another, thereby delimiting a volume; - the first stiffening structure (110) has a higher stiffness and a higher strength than the second stiffening structure (120); - the second stiffening structure (120) is designed to collapse when a threshold value is exceeded, characterized by , - that the second stiffening structure (120) is constructed from at least two chambers (123), wherein - the chambers (123) of the second stiffening structure (120) and / or the second stiffening structure (120) are made of plastic - and / or that the chambers (123) of the second stiffening structure (120) and / or the second stiffening structure (120) are made of deformable materials, foams and / or elastomers. [2] Frame (100) for a battery box according to claim 1, characterized by that the first stiffening structure (110) has a different geometry than the second stiffening structure (120). [3] Frame (100) for a battery box according to one of the preceding claims, characterized by that the foams and / or elastomers are arranged flatly and / or locally between the first stiffening structure (110) and the receiving structure (130). [4] Frame (100) for a battery box according to one of the preceding claims, characterized by that the chambers (123) made of plastic have local ribs (121), wherein the local ribs comprise predetermined breaking points and / or wherein the local ribs (122) are designed with kinks. [5] Frame (100) for a battery box according to claim 4, characterized by that the local ribs (121) have a reduced cross-section and / or a curved S-shape. [6] Frame (100) for a battery box according to one of the preceding claims, characterized by that the at least two chambers (123) of the second stiffening structure (120) are spaced apart from one another and / or that chambers (123) of the second stiffening structure (120) are of different geometric configurations so that they collapse at different threshold values. [7] Frame (100) for a battery box according to one of the preceding claims, characterized bythat the first stiffening structure (100) is constructed from a plurality of chambers (112) and / or that some, but not all, of the chambers (112) of the first stiffening structure (110) are reinforced, wherein the reinforced chambers (112) are arranged parallel to the second stiffening structure (120). [8] Frame (100) for a battery box according to one of the preceding claims, characterized by that the first stiffening structure (110) and the second stiffening structure (120) run parallel to the receiving structure (130) and are formed axially symmetrically to the X-axis or that the first stiffening structure (110) and the second stiffening structure (120) completely enclose the receiving structure (130) in an XY plane.

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