WO2019174730A1

WO2019174730A1 - Underride guard for a battery housing

Info

Publication number: WO2019174730A1
Application number: PCT/EP2018/056467
Authority: WO
Inventors: Daniel Nierhoff; Georg PAUL
Original assignee: Thyssenkrupp Steel Europe Ag; Thyssenkrupp Ag
Priority date: 2018-03-15
Filing date: 2018-03-15
Publication date: 2019-09-19

Abstract

The present invention relates to an underride guard (1) for a battery housing (10), in particular for an electrically propelled vehicle or a vehicle having a hybrid drive system, which guard consists of a steel sheet having a modulus of elasticity > 210 GPa.

Description

Underride protection for a battery case

Technical area

The present invention relates to an underrun protection for a battery case, in particular for an electrically driven vehicle or a vehicle with hybrid drive, as well as an electrically driven vehicle or a vehicle with hybrid drive comprising a battery housing with the underrun protection according to the invention.

Technical background

The increasing or prolonged electrification of vehicles, in particular of automobiles, and the simultaneous customer request for long ranges of such vehicles, requires the development of high-performance battery concepts. In particular, battery housing, which receive the battery modules or in which the battery modules are received, usually have a substantial extent in the transverse and longitudinal direction of the vehicle and are mounted centrally, in particular below the passenger compartment below the vehicle floor panel. Among other things, the battery housing protects the battery modules against damage as well as dissipates the heat generated by the battery modules during the drive of the vehicle. This results in complex requirements with regard to the factors installation space, crash performance, weight, tightness, etc.

In particular, the protection of the battery modules from penetrating from below foreign bodies is due to their particularly exposed position on the vehicle floor of great importance. For a good utilization of the available installation space, the distance between the sensitive battery modules and the bottom floor of the housing is typically less than 25 mm. Penetrating debris must therefore be decelerated efficiently over very short distances before the battery modules are damaged and a critical short circuit can occur. For this purpose, different concepts using an underrun protection are shown in the prior art. These usually consist of a cassette-like, supporting structure of longitudinal and / or transverse support elements and a downwardly concluding plate made of a particular heavy duty material such as steel.

In various simulations it has been found that such a plate is exposed to a tensile stress on the impact of a foreign body in particular. Bending shares are due to the low depth of bury and the considerable size of the claimed, in particular inside, unsupported surface barely present. In this respect, it is above all the tensile stiffness of the underride protection that plays a special role at least until material failure and penetration. In the following, the tensile stiffness is the product of modulus of elasticity and loaded cross-sectional area. A significant improvement in safety can be achieved by increasing the tensile stiffness of the underride guard.

An increase in the tensile stiffness can be achieved on the one hand by increasing the loaded cross section. Since a mostly cassette-like structure of the underrun protection is primarily determined by the size and positioning of the overlying battery modules, this is mainly due to an increase in the plate thickness. Among other things, thick aluminum plates, flybridge materials made of metal and plastic, fiber-reinforced plastic overlays on metal sheets, etc. are used. However, this approach may be counterproductive, since, while maintaining the installation space, an increase in the plate thickness simultaneously accompanies a reduction of the free deformation space , For example, a thicker plate will infiltrate the battery module sooner than a thinner plate with comparable performance. The increase in plate thickness inevitably causes unwanted weight gain in vehicle construction.

Another way to increase the tensile stiffness is the choice of a material with the highest possible modulus of elasticity (Young's modulus). The material steel, with its particularly high modulus of elasticity of about 210 GPa, is technically and economically suitable for such an application. However, there is further optimization potential.

Summary of the invention

The invention is therefore based on the object to provide underrun protection with higher Zugstei- figkeit for a battery case, in particular for an electrically driven vehicle or a vehicle with hybrid drive.

This object is achieved by an underrun protection with the features of patent claim 1.

Advantageous embodiments and variants of the invention will become apparent from the dependent claims and the description below.

According to the invention, an underrun protection for a battery housing, in particular for an electrically driven vehicle or a vehicle with hybrid drive, consisting of a Sheet steel with an E-modulus> 210 GPa, in particular with an E-modulus> 212 GPa, preferably with an E-modulus> 215 GPa, particularly preferably with an E-modulus> 220 GPa.

To increase the tensile stiffness, the choice is not to increase the underrun protection in its thickness, which in addition to a reduction of the existing deformation space also leads to an increase in the total weight of the battery case, but to steels with higher compared to conventional steels modulus use.

The battery modules and the usually cassette-type support structure located below these are usually rectangular. It forms below the battery modules rectangular surfaces without further inner support with two short and two long sides of the magazine, which are particularly at risk. According to a first embodiment, the steel sheet has an anisotropic orientation of the modulus of elasticity. The underride protection with an anisotropic E-module terminating from below the battery housing should be connected in such a way that the direction of the highest modulus of elasticity is oriented in the direction of the longer compartment side or parallel to maximize the performance. When loading the smaller cross-sectional area, the higher modulus has a supporting effect and contributes to increasing the tensile stiffness.

In particular, the steel sheet on one or both sides of a corrosion protection coating on, for example, zinc-based, which has been applied in particular electrolytically. Alternatively, a fire-coated coating is conceivable, based on zinc and on aluminum, such as zinc-magnesium, zinc-aluminum, zinc-aluminum-magnesium, zinc-egg sen, aluminum-silicon, aluminum-zinc, etc.

The production of steels with a higher E-modulus or anisotropic E-modulus is known, for example, from the prior art. For example, steel sheets may be used that are textured, dressed and / or regrooved by a dedicated process, s. by way of example EP 1 731 627 A1; EP 1 806 421 A1; Park et al., Acta. Mat. Vol. 46 (1998), no. 10, 3371-3379.

It is particularly preferable to use textured steel sheets which are rolled, in particular cold-rolled, and have a texture (crystallography) with preferably oriented crystals and, associated with this, anisotropy sets in the steel. The steel sheets can Depending on the texture, it can be used as hard as a roller. If, however, the desired degree of deformation of the steel sheet is not ensured, optional annealing may be carried out, in which case the temperature and the duration of this heat treatment (recovery annealing) are coordinated in such a way that the texture substantially remains in comparison with the state before the heat treatment or only a minor change is allowed. The recovery annealing preferably takes place at temperatures of up to 600 ° C., in particular up to 550 ° C., preferably up to 500 ° C., since temperatures above this would lead to recrystallization in the steel sheet. The recovery annealing can be done conventionally in continuous annealing or preferably in bell annealing. The steel sheets can subsequently also be provided with a corrosion protection coating, for example, be galvanized galvanized. Zinc or zinc-based fire coating is also conceivable, but the appropriate temperatures should not be exceeded, which could lead to recrystallization and thus to a change in the texture.

The texture or the modulus of elasticity in the steel sheets can be determined by tensile testing (DIN EN ISO 6892-1: 2017) or the direction of the crystals or the direction of the (higher) modulus of elasticity by electron backscattering, known in the art as EBSD (electron backscatter diffraction).

Alternatively, a specific texture can also be carried out, in particular following the application of a corrosion protection coating, for example by means of skin-forming and / or temper rolling. This means that the steel sheet or steel strip is first exposed to a coating and then the adjustment of the texture to increase the modulus of elasticity can be done by plastic deformation by thickness reduction. In this case, it is necessary to provide a force with corresponding thickness decreases of at least 1.5%, in particular at least 2%, preferably at least 2.5%, particularly preferably at least 3%, by increasing the modulus of elasticity by appropriate orientation of the crystals cause. The thickness reduction should be such and not exceed a certain value that no interruption or tearing off of the corrosion protection coating on the surface of the steel sheet / strip takes place and a corresponding corrosion protection can continue to be ensured. This certain value depends on the thickness of the steel sheet and the thickness of the corrosion coating and can be relatively easily determined by appropriate trials (trial and error). Alternatively, for example, steel sheets may be used which are particle-reinforced, in particular ceramic particles, for example SiC, Al ₂ O ₃ , TiC, ZrO ₂ and / or TiB ₂ particles which, individually or in combination in the steel matrix, have a proportion from 5 to 40% by weight, in particular from 10 to 35% by weight, preferably from 15 to 30% by weight, s. by way of example EP 2 703 509 A1.

Alternatively, for example, steel sheets may be used which comprise refractory alloying elements, such as Cr, Mo and / or W, of at least 0.3% by weight, in particular of at least 1.0% by weight, preferably of at least 1, 5 wt .-%, particularly preferably of at least 2.0 wt .-%, individually or in total, and thus lead to a higher modulus of elasticity. The modulus of elasticity depends directly on the binding forces in the atomic lattice, whereby the binding forces also influence the melting point. The modulus of elasticity is essentially proportional to the melting point.

Depending on the design and / or manufacturing process, E-modules> 225 GPa, in particular> 230 GPa, preferably> 235 GPa, can be set in the steel sheet.

The material thickness of the steel sheets is 0.7 to 4.0 mm, in particular 0.8 to 3.0 mm, preferably 0.8 to 2.5 mm.

According to a second aspect, the invention relates to an electrically driven vehicle or vehicle with hybrid drive, in particular a passenger vehicle, commercial vehicle, special vehicle, preferably bus, omnibus, a track-bound vehicle, preferably a tramway or person-conveying wagon, comprising a battery housing with an invented Underride protection according to the invention.

Short description of the drawing

1 shows a schematic sectional view of an embodiment of a first battery housing with an underrun protection according to the invention.

2 shows a schematic bottom view and a schematic sectional view according to line AA of an embodiment of a second battery housing with an underrun protection according to the invention. Description of the preferred embodiment

In Fig. 1 is a schematic representation of an embodiment of a first battery housing (10) is shown. The battery housing (10), which is provided for an electrically driven vehicle or a vehicle with hybrid drive (not shown), in particular an electrically driven passenger vehicle or hybrid-powered passenger vehicle, has a battery receiving space (11), for example in the form of a one-piece Tub (13) on. The trough (13) has a circumferential flange (13.1), via which the trough (13) is connected to a housing frame (14). The housing frame (14) runs along the edge of the battery housing (10) and has a pentagonal cross-section. Other cross-sections / cross-sectional shapes are conceivable. The battery housing 10 can be connected to the body of a vehicle, in particular on the vehicle floor (not shown), via the housing frame (14). For this purpose, the housing frame (14) a plurality of openings (17), via which the battery case (10) can be screwed to the body. Furthermore, the battery housing (10) has a cover (12) with which the trough (13) can be closed. The lid (12) also has a circumferential flange (12.1). By means of corresponding openings (18) in the respective flange (12.1, 13.1) and in the housing frame (14), the trough (13) can be connected to the lid (12) on the housing frame (14) by means of a screw connection. The battery housing (10) has an underrun protection (1) according to the invention, which is arranged under the trough (13) and releasably secured to the housing frame (14) via a flange (19), for example by means of a screw connection. The underrun protection can alternatively also be attached permanently.

The underrun protection (1) consists of a steel sheet with an E-modulus> 210 GPa, in particular with an E-modulus> 212 GPa, preferably with an E-modulus> 215 GPa, particularly preferably with an E-modulus> 220 GPa, and protects the battery case (10) from impinging on the bottom of foreign objects.

The battery housing (10) further comprises a space (20), also called cooling space or deformation space, in which in particular cooling elements for cooling and other elements are arranged (not shown), on which between the tub (13) and the Unterfahr- protection (1) is formed. Within the battery receiving space (11), longitudinal and / or transverse beams (15) and, alternatively or additionally, also between the trough (13) and underbody protection (1), longitudinal and / or transverse beams (16) may be arranged, which in the battery compartment housing (10) provide additional rigidity. In Fig. 2 is a schematic bottom view and a sectional view along line AA of an embodiment of a second battery case (10) is shown. In contrast to FIG. 1, the battery receiving space (11) can be formed by a trough (13) or alternatively and preferably be assembled from individual components, not shown here. In example, the side walls of the battery receiving space (11) of profiles and the floor are composed of a sheet metal. The underrun protection (1) can have stampings (2) in comparison to FIG. The openings or holes (4, 5, 6) are used for the detachable connection of the underrun protection (1) to the battery housing (10), wherein the openings (4) have a connection to the longitudinal and / or transverse beams (15, 16 ), the openings (5) allow a connection to the housing frame (14) and the openings (6) a connection to the front and rear ren side walls (in the installed state in the direction of travel). The openings (4, 5, 6) are only to be understood as examples.

The dash-lined areas illustrated in FIG. 2 define unsupported areas (3) of the underrun protection (1), each having two short flat sides (3.1) and two long sides (3.2), which are particularly at risk from below. According to the invention, the underride protection (1) consists of a steel sheet with an E-modulus> 210 GPa, in particular with an E-modulus> 212 GPa, preferably with an E-modulus> 215 GPa, particularly preferably with an E-modulus> 220 GPa, and protects the battery housing (10) from foreign bodies that strike from below. The double arrows (7) in the unsupported surfaces (3) symbolize the anisotropy or the direction of the increased modulus of elasticity of the underrun protection (1), which is achieved, for example, by a rolled, in particular cold-rolled, preferably roll-hardened and optionally recovery annealed steel sheet is provided, which preferably has a one or both sides applied corrosion protection coating based on zinc. The underride protection (1) with an anisotropic E module, which terminates from below the battery housing, is connected in such a way that the direction (7) of the highest modulus of elasticity is oriented in the direction of the longer compartment side (3.2) or parallel thereto , When loading the smaller cross-sectional area, the higher modulus has a supporting effect and contributes to increasing the tensile stiffness. Alternatively, it is also possible to use particle-reinforced steel sheets which, in comparison to conventional steel sheets, have a higher modulus of elasticity in all directions.

The invention is not limited to the embodiments shown, but the individual features can be combined with each other. Particularly preferably, a battery housing with the underrun protection according to the invention in passenger vehicles, commercial vehicles, Lorries, special vehicles, buses, buses, whether with hybrid or pure electrical drive rule, but also in track-bound vehicles, such as trams or passenger-carrying wagons are used.

Claims

claims

1. Underride protection (1) for a battery housing (10), in particular for an electrically driven vehicle or a vehicle with F hybrid drive, consisting of a steel sheet with an E-modulus> 210 GPa.

2. Underride protection according to claim 1, wherein the steel sheet has an anisotropic orientation of the modulus of elasticity.

3. Underride protection according to claim 2, wherein the steel sheet is hard-hardened and optionally heat-treated.

4. Underride protection according to claim 2 or 3, wherein the underrun protection (1) unsupported surfaces (3), each with two short flat sides (3.1) and two long Fachsei- States (3.2), wherein the direction (7) of the highest Modulus of elasticity in the direction of the longer side (3.2).

5. underrun protection according to claim 1, wherein the steel sheet is particle-reinforced.

6. Underride protection according to one of the preceding claims, wherein the steel sheet on one or both sides has a corrosion protection coating, in particular based on zinc.

7. Underrun protection according to one of the preceding claims, wherein the material thickness of the steel sheet is 0.7 to 4.0 mm, in particular 0.8 to 3.0 mm, preferably 0.8 to 2.5 mm.

8. Electrically driven vehicle or vehicle with hybrid drive, in particular a passenger vehicle, commercial vehicle, special vehicle, preferably bus, bus, a track-bound vehicle, preferably tram or passenger-carrying wagon, comprising a battery housing (10) with an underrun protection (1) after one of nem previous claims.