HEAT-FORMED AND PRESS-HARDENED BATTERY PAN

Description

[0001] The present invention relates to a hot-formed and press-hardened battery tray for an electric vehicle according to the features in the preamble of claim 1.

[0002] It is known from the prior art to use battery trays in motor vehicles, particularly in electric vehicles. Such battery trays have a battery compartment for holding traction batteries. The battery compartment is closed with a lid. Such a battery compartment is usually located in the underfloor area of ​​a motor vehicle. The battery compartment typically extends over a large part of the underfloor area, especially the passenger compartment. Longitudinal sides of the battery compartment are formed laterally in the area of ​​the sills. Transverse sides are formed at the front and rear. The transverse sides are shorter than the longitudinal sides.

[0003] From the prior art, for example from DE 10 2016 116 729 B4, a battery housing for an electrically powered vehicle is known which is manufactured using a deep-drawing process.

[0004] From CN 115 732 831 A a battery carrier is known which is manufactured by hot forming and press hardening.

[0005] The object of the present invention is to provide, starting from the prior art, a battery tray which can be manufactured in a simplified manner compared to the prior art, is optimized with regard to the internal receiving space for receiving batteries and is improved in its crashworthiness in the case of a motor vehicle.

[0006] The aforementioned problem is solved according to the invention in a battery tray with the features in claim 1.

[0007] Advantageous embodiments of the present invention are described in the dependent claims.

[0008] The battery tray is intended for an electric vehicle. It is manufactured as a hot-formed and press-hardened component from a sheet steel blank. The sheet steel blank is preferably made of a hardenable steel alloy, for example, 22MnB5. For hot forming and press hardening, the blank may, for example, have a scale or corrosion protection layer. This layer may be based on aluminum-silicon or zinc, or a combination thereof. The material thickness is between 0.8 mm and 2.5 mm, preferably between 1.0 mm and 2.2 mm, and particularly preferably between 0.8 mm and 1.5 mm. For hot forming, the blank is first heated to above the austenitizing temperature, i.e., above 900°C, then hot-formed in a press, and subsequently cooled or quenched and hardened.In this process, tensile strengths Rm greater than 1000 MPa, in particular greater than 1350 MPa, can be achieved at least in sections, preferably over the entire surface of the battery tray.

[0009] The battery tray itself has a tray-shaped housing. A base is provided for this purpose. The base is preferably flat. However, various reinforcing ribs or cross braces can be incorporated into the base. These reinforcing structures can increase the base's rigidity. They can also increase crash stiffness. Ribs can also be incorporated into the base, so that, when coupled with another sheet of the base, a cooling channel structure is formed. This allows the base to act as a cooling surface for the batteries arranged in the battery tray when a cooling medium is passed through it.

[0010] Side walls extend from the floor, or, in relation to the vehicle's vertical direction, rise up. A flange projecting outwards around the battery tray is formed at the top of the side walls. This flange serves both to stiffen the structure and to provide a cover for the battery tray.

[0011] According to the invention, the battery tray is characterized in that the side walls on the longitudinal sides, hereinafter also referred to as longitudinal side walls, and the side walls on the transverse sides, i.e., the head and rear sides, hereinafter also referred to as transverse side walls, are oriented at an angle greater than 1° to a vertical or to the vehicle's vertical direction when the battery tray is installed. According to the invention, the angle of the longitudinal side walls is further provided that it is greater than the angle of the transverse side walls. This results in an optimum balance between manufacturability in the deep-drawing or press-forming process and the available installation space for accommodating batteries. Furthermore, the installation space is particularly optimized for electrical connections of the battery modules within the battery tray and for the connection of a cooling system, which can also be designed to pass through or extend through the battery tray.Furthermore, improved crash characteristics in frontal and side impacts result from at least one of the walls being steeper, i.e., having a lesser inclination to the vertical. Specifically, these are always two opposing walls that have the same inclination.

[0012] A key aspect of the invention is that the side walls running transversely to the vehicle, from one left to one right side, are steeper, i.e., they have a shallower inclination to the vertical. Conversely, the side walls running longitudinally to the vehicle, i.e., from the front to the rear, are less steep in cross-section, particularly at a greater angle to the vertical than the side walls running transversely to the vehicle.

[0013] The angle of the transverse side walls to the vertical is preferably 1° to 6°. A more preferred angle is 2° to 6°, and more preferably 3° to 6°. The angle of the longitudinal side walls to the vertical is preferably 8° to 20°, and more preferably 13° to 20°.

[0014] Due to the different angles of transverse side walls and longitudinal side walls, an asymmetrical design of the corners or corner areas results in the respective transition area from transverse side wall to longitudinal side wall.

[0015] In a further preferred embodiment, the corners or corner areas are arranged or formed offset to the outside. "Outward" refers to the interior of the battery tray. Compared to the transverse and / or longitudinal side wall, each corner area is offset at least partially outward in the longitudinal and / or transverse direction of the vehicle. This means that at least part of the corner area projects outward beyond the transverse or longitudinal side wall. This offers several advantages. Firstly, it optimizes the forming process. According to the invention, the local degree of stretching during the production of the corners is reduced, thus preventing breakage or tearing.

[0016] Furthermore, the available installation space in the battery tray is optimized by the outwardly shaped corners and corner areas. Improved crash performance is also achieved, as the outward shaping stiffens the corner area. Additionally, the corner area protrudes and can thus, in the event of a crash, cushion the initial impact, acting like a crash box. Another advantage of the outwardly shaped corner is that a crash frame attached to the outside or inside of the respective side walls can be shortened in certain sections, resulting in material and weight savings. In particular, a reinforcing profile can be attached to the outside and / or inside of the side wall. This creates a hollow profile in the respective cross-section. However, the reinforcing profile does not necessarily have to extend the entire length of the side wall in certain sections.The reinforcement profile then extends lengthwise only to the beginning of the corner area, but can also extend beyond it.

[0017] Furthermore, according to the invention, the corner areas are designed such that a curved plane rises from the ground plane with a continuously increasing curvature. This plane is curved around a two-point line, which lies in the xy-plane, i.e., the plane spanned by the transverse and longitudinal directions of the vehicle. The curvature of a corner plane is then formed around this straight line or two-point line. The curved surface is thus two-dimensionally curved, but not three-dimensionally. Within the scope of the invention, this means that the plane has a sectionally cylindrical curvature, but not a sectionally spherical curvature. At each transition of the curved surface to the transverse or longitudinal side wall, a radius is formed with which the curved surface merges into the respective side wall.

[0018] The curved surface extends along the vertical direction of the vehicle, preferably over a maximum of 85% of the height of the battery tray, and in particular over approximately 50% to 75% of the height of the battery tray. The remaining height section of the battery tray or side walls is then formed as a transition radius from the transverse side wall to the longitudinal side wall, whereby the radius may vary. The height of the battery tray is preferably more than 50 mm, more preferably more than 80 mm, and in particular more than 100 mm, but not more than 150 mm.

[0019] The curved surface preferably has a height and a width in a cross-section. The cross-sectional area lies in the vertical direction of the vehicle. The height thus extends in the force-vertical direction. The width lies in the plane spanned by the transverse and longitudinal directions of the vehicle. The ratio of height to width of the curved surface is preferably 0.5 to 1, particularly 0.65 to 0.85. This ratio of the curved surface is especially preferred at a 45° angle of the corner. This means, in plan view, exactly at the center of the corner, as well as in the following view... Figure 3 and Figure 9 shown. The aforementioned ratio therefore means that the width has a greater value than the height.

[0020] Preferably, the outer flange can have a rectangular contour when viewed from above, i.e., from the vertical direction of the vehicle. This means that the battery tray can be closed with a cover, and the cover would then also have a rectangular contour. However, the flange can also have a constant width. In particular, with outwardly projecting corner areas, the flange then does not have a rectangular contour when viewed from above, but rather follows the outwardly projecting corner areas.

[0021] Furthermore, the battery tray can have various corrugations or reinforcing structures. These can, for example, serve as underride protection. Accordingly, corrugations would preferably be designed to face downwards in the vertical direction of the vehicle when the battery tray is installed, meaning they would protrude downwards from or extend beyond the bottom of the battery tray.

[0022] Furthermore, openings for electrical connections and / or coolant lines may be incorporated into the side walls, particularly the longitudinal side walls. These can be created, for example, by laser cutting after hot forming and press hardening, or even during the preparation of the circuit board. The base of the battery tray may also feature a cooling channel structure. This can be embossed in one piece with a corrugated pattern and then sealed with a closing plate.

[0023] Preferably, a lid used to close the battery tray can also have a cooling channel structure. In this case, the present invention would then comprise a battery tray assembly, a battery tray, and a lid closing it. The lid is then placed and joined onto the flange using a sealant, for example, by screwing it on.

[0024] Further advantages, features, properties, and aspects of the present invention are the subject of the following description. Preferred embodiments are illustrated in figures. These serve to facilitate understanding of the invention. The individual embodiments can be combined with one another as desired without altering the scope of disclosure. The figures show... Figure 1 shows a perspective view of a battery tray according to the invention, Figure 2 shows a perspective view from below, Figure 3 shows a top view of the battery tray according to the invention, Figure 4 shows a side view of the battery tray according to the invention, Figure 5 shows the section line VV to Figure 3 , Figure 6 Section line VI-VI to Figure 3 Figure 7 is a horizontal section through a corner area, Figure 8 is a horizontal section through a corner area, and Figure 9 is a longitudinal section view through a corner area according to section line IX-IX. Figure 3 .

[0025] The same reference symbols are used in the figures for identical or similar components, even if a repeated representation or description is omitted for the sake of simplicity.

[0026] Figure 1Figure 1 shows a perspective view of a battery tray 1 according to the invention. The battery tray 1 has a base 2. The base 2 extends primarily in a plane in the longitudinal direction X and the transverse direction Y of the vehicle. Various stiffening geometries are formed in the base 2. For example, transverse struts 3 are formed in the form of beads 4. These extend downwards with respect to the vertical direction Z of the vehicle. Furthermore, additional stiffening beads 4 are embossed. These project into an interior space of the battery tray 1. Side walls in the form of two longitudinal side walls 5 extend from the base 2. The longitudinal side walls 5 are oriented in the longitudinal direction X of the vehicle. In addition, two transverse side walls 6 are present. The transverse side walls 6 are arranged at the front and rear with respect to the longitudinal direction X of the vehicle and themselves extend in the transverse direction Y of the vehicle.A flange 7 is formed around the outer edge of the upper side walls, projecting outwards. The flange 7 itself lies in a plane spanned by the transverse and longitudinal directions X, Y of the vehicle. The longitudinal and transverse side walls 5, 6 are each connected to one another via a corner section 8. A curved surface 9 extending from the base 2 is formed in the corner section 8. The surface itself is a two-dimensional curved surface 9 and is cylindrical segment-shaped with a varying radius. The curved surface 9 does not extend over the entire height of the battery tray 1, but preferably over less than 85% of the height. Openings 10 may also be provided in the side walls for the passage of cooling channels and / or electrical connections. The longitudinal side walls 5 and transverse side walls 6 each transition from the base 2 into the side wall and from the side wall into the flange 7 with a transition radius 11.

[0027] Figure 2 The perspective view from below is shown. It is clearly visible here that the respective curved surface 9 transitions from the plane of the floor 2 in the corner areas 8.

[0028] Figure 3 Figure 1 shows a top view of the battery tray 1 according to the invention. It can be clearly seen that the respective corner areas 8 are offset outwards with respect to an interior space 12 of the battery tray 1, in particular offset outwards with respect to the longitudinal sides or transverse sides.

[0029] Figure 4Figure 1 shows the battery tray 1 according to the invention in a side view. It is clearly visible that the curved surface 9 does not extend over the entire height 13, but only over a portion of less than 85%. Above the curved surface, relative to the vehicle's vertical direction Z, the transverse side wall 6 and longitudinal side wall 5 are connected in the XY plane via a radius 14. The transition from the longitudinal side wall 5 to the curved surface 9 and from the curved surface 9 to the transverse side wall 6 is each formed with a transition radius 14.

[0030] Figures 5 and 6 show section line VV and VI-VI from Figure 3The feature according to the invention can be seen in that the angle α 15 of the longitudinal side wall 5 is larger, in particular twice as large, compared to the angle β 16 of the transverse side wall 6. Specifically, the angle α has an angular range between 8° and 20°, preferably 13° to 20°, whereas the angle β has an angular range between 1° and 6°, preferably between 3° and 6°.

[0031] Figure 7 shows a cross-sectional view according to section line VII-VII from Figure 4 In plan view. It shows that the curved surface 9 of the corner area 8 transitions into the transverse side wall 6 and the longitudinal side wall 5 respectively with a transition radius 14.

[0032] Figure 8 shows a cross-sectional view according to section line VIII-VIII from Figure 4. Here it can be seen that in an upper area relative to the vertical direction Z, the transverse side wall 6 transitions into the longitudinal side wall 5 with a radius of 16. The curved surface 9 is thus defined by the intersection line of Figure 8 already expired.

[0033] Figure 9 shows a longitudinal section view through a corner area 8 according to the section line IX-IX from Figure 3 The curved surface 9 rises from the ground plane and then transitions via the height 13 at the upper edge into the outwardly projecting flange 7. The ratio of height h to width b of this curved surface 9 is 0.5 to 1, preferably 0.65 to 0.85. Reference symbol:

[0034] 1 - Battery tray 2 - Floor 3 - Cross brace 4 - Reinforcing ribs 5 - Longitudinal side wall 6 - Transverse side wall 7 - Flange 8 - Corner area 9 - Curved surface 10 - Opening 11 - Transition radius 12 - Interior 13 - Height 14 - Transition radius 15 - Vertical 16 - Radius α - Angle to 5 β - Angle to 6 h - Height of the curved surface 9 b - Width of the curved surface 9 X - Longitudinal direction of the vehicle Y - Transverse direction of the vehicle Z - Vertical direction of the vehicle

Claims

1. A battery tray (1) for an electric vehicle, manufactured as a thermoformed and press-hardened component from a sheet steel blank, having a base (2) and side walls (5, 6) rising from the base (2) with an outwardly projecting flange (7) circumferentially around the top of the battery tray (1), wherein the side walls (5) on longitudinal sides of the battery tray (1) are oriented at an angle α and the side walls (6) on transverse sides are oriented at an angle β, greater than 1° to the vehicle vertical direction (Z) in the installed state of the battery tray (1), wherein, in each corner area (8), the base (2) of the battery tray (2) transitions into a curved surface (9) such that a transition radius (14) of the curved surface (9) to a transverse side wall (6) is obtained and a transition radius (14) of the curved surface (9) to a longitudinal side wall (5) is obtained, characterized in that the angle α of the longitudinal side walls (5) is greater than the angle β of the transverse side walls (6).

2. The battery tray (1) according to claim 1, characterized in that the angle β is 1° to 6°, preferably 3° to 6° and / or that the angle α is 8° to 20°, preferably 13° to 20°.

3. The battery tray (1) according to any one of the preceding claims, characterized in that corner areas (8) in the transition of each transverse side wall (6) to a longitudinal side wall (5), with reference to an interior of the battery tray (1), are formed offset to the outside.

4. The battery tray (1) according to any one of the preceding claims, characterized in that the angle α is twice as large as the angle β.

5. The battery tray (1) according to any one of the preceding claims, characterized in that the curved surface (9) has a section-wise cylindrical curvature with a changing radius.

6. The battery tray (1) according to any one of the preceding claims, characterized in that the curved surface (9) extends from a base (2) of the battery tray (1) over a maximum of 85 % of the height, in particular over 50 % to 75 %, most preferably 50 % to 65 % of the height of the battery tray (1).

7. The battery tray (1) according to any one of the preceding claims, characterized in that the outer circumferential flange (7) has a rectangular contour in plan view, such that the battery tray (1) can be closed with a lid.

8. The battery tray (1) according to any one of the preceding claims, characterized in that a reinforcing profile is coupled to the battery tray (1) in longitudinal sections on the transverse sides and / or longitudinal sides (5, 6), in particular the corner areas (8) are recessed.

9. The battery tray (1) according to any one of the preceding claims, characterized in that the reinforcing profile forms a hollow profile in cross-section with the respective side wall (5, 6), optionally further reinforcing elements are disposed, in particular in the hollow chamber.

10. The battery tray (1) according to any one of the preceding claims, characterized in that it has a tensile strength Rm greater than 1000 MPa, preferably greater than 1350 MPa.

11. The battery tray (1) according to any one of the preceding claims, characterized in that the ratio of height (h) to width (b) of the curved surface (9) is between 0.5 and 1, preferably between 0.65 and 0.85.

12. The battery tray (1) according to any one of the preceding claims, characterized in that the outer circumferential flange (7) has a substantially constant width.