Patent Application
20230006297
The invention relates to a battery housing having the features of the preamble of claim 1.
Vehicles driven by electric motors, such as electric vehicles or hybrid vehicles, are equipped with powerful and spacious battery modules. These are typically located in the floor region of the vehicle to keep the vehicle's center of gravity close to the around. The battery modules are arranged in a battery housing. The battery housing has a frame with a floor connected thereto. The battery housing can be composed of a frame part and a floor, but embodiments are also conceivable in which a trough, which has a peripheral frame and a floor formed thereon, is used as the battery housing. Typically, the battery modules in the battery housing are attached to the frame and rest on the floor of the battery housing. The battery modules are typically lithium-ion batteries, typically high-voltage batteries. These battery modules must not be damaged. In the event of damage, the risk thereby posed is not insignificant. Battery housings of this type are designed with regard to the frames or frame structures thereof in order to handle or absorb lateral impact forces, at least to a certain extent, without damaging the battery modules contained therein. However, due to insufficient installation height, the floor of a battery housing cannot be protected with the hollow chamber profiles that are typically used as the frame structures. Collision protection is therefore desired because, in the event the floor of the vehicle's battery housing makes contact with an obstacle, deformation of the battery modules contained therein should also be avoided, particularly in the case of battery housings with a large surface area.
DE 10 2017 119 436 A1 discloses a battery housing in which the floor is formed from an extruded aluminum hollow chamber profile. This provides a structure that has sufficient rigidity for collision protection.
If greater rigidity is desired, other materials, such as high-strength alloys, are also used to provide collision protection. For example, high-strength titanium plates are also used for this purpose. However, these have the disadvantages of high costs, increased processing effort, and a higher weight.
A temperature-control device for a battery housing is known from DE 10 2015 008 942 A1. This device is located in the floor region of the battery housing or forms ft. The temperature-control device comprises two sheets with a corrugated profile, which are arranged one above the other at right angles with respect to the longitudinal extension of the profile of the channels formed therewith. The profiled sheets lie loosely on top of each other to provide glide paths to allow limited deformation. In the event of contact, forces acting on the floor should be dissipated via the sliding paths and not be passed on to the interior of the battery housing.
DE 10 2017 103 653 A1 discloses a battery housing which has two floor sheets spaced apart from one another. A profiled reinforcement sheet is arranged between these floor sheets.
DE 10 2011 107 607 A1 discloses a cooling plate that is attached to the top of a battery housing.
DE 10 2016 213 832 A1 discloses a battery housing made from an extruded profile.
Against the backdrop outlined above, it is the object of the invention to provide a battery housing which is equipped with lightweight collision protection which can be produced inexpensively and which also only requires a small amount of installation space.
This object is achieved by means of a generic battery housing of the type mentioned at the outset and having the features of claim 1.
The core of the invention is that the floor is designed in a sandwich construction in the manner described. The special sandwich construction not only ensures a simple and inexpensive structure, but also creates a especially effective reinforcement of the floor, which means that the floor is equipped with collision protection that only requires a small amount of installation space, but still has an especially high level of rigidity.
The sandwich construction includes a lower sheet and an upper sheet. The two sheets are arranged at a distance from one another. They represent the outer straps of the sandwich construction. A structural sheet is arranged between these two sheets, by means of which structural sheet the two sheets are connected to one another in a manner that is resistant to tension, pressure, and shear. The profile of the structural sheet is corrugated in its cross-section at least in sections. The profiling consists of a repeating sequence of structural sections. Such a sequence of sections includes the following sections, which transition into one another in the following order:
The first contact section is connected to the lowerheet. The second contact section is connected to the upper sheet. The two contact sections lie against the lower or upper sheet over a certain extension in the cross-sectional direction of the structural sheet. The structural sheet thus makes contact with the lower sheet and the upper sheet with a respective surface contact. The two bridging sections are arranged in the distance direction of the upper sheet to the lower sheet and connect the contact sections to each other. The sequence of sections described above can, of course, also begin at another section, for example the first bridging section. The sequence of sections then extends up to (and includes) the first contact section. In the sequence of structural sections described, the bridging sections are spaced apart from one another by the width of the second contact section. According to a first embodiment, the profiling of the structural sheet extends over the entire longitudinal extension of the structural sheet. Due to this structuring, the structural sheet has a form of alternating channels which open to the lower sheet and the upper sheet in an alternating manner.
In another embodiment, the structural sheet has local support projections. These are typically arranged in the manner of a grid. These support projections can be introduced into a blank to form the structural sheet by means of an embossing or deep-drawing process. A first contact section is provided on the outside of such a support projection, and a second contact section is provided by the surface area of the structural sheet.
If it is not produced in one piece as part of the structural sheet, such a support projection can also be glued onto the structural sheet and made from a material that is different than that of the structural sheet. It is also possible to design the support projections as solid cylinders, for example glued onto a floor sheet of the structural sheet.
The orientation of the bridging sections between the two sheets extends in the direction of the distance between the two sheets. The term “distance direction” used in the context of these statements is to be understood as meaning the direction in which a first contact section connected to a second contact section by means of a bridging section. In the end section thereof which transitions into the adjoining contact section, the bridging sections have a transition section that is designed with a radius.
Provision can preferably be made for the angular extension of the radius to be 70° or more. If the transition sections located opposite one another do not transition directly into one another, the section located in between is typically straight and forms an angle of 90°±10° with the two sheets. The distance direction is therefore the direction in which the forces to be taken into account, acting orthogonally from the outside on the lower sheet, are transferred to the upper sheet in or largely in the direction of force flow. The transition sections preferably extend over 80°, more preferably over 85°, and especially preferably over 90° in relation to the contact sections. Depending on the distance between the upper and lower sheets, the transition sections of the bridging sections can transition into one another. In many cases, in order to achieve the desired distance between the two sheets, a straight middle section will be included between the transition sections of the bridging sections, which middle section preferably extends at right angles to the two sheets. An inclination of 5° to 10° is tolerable, especially if the extension of the middle section in the direction of the thickness of the sandwich construction is less than the extension of the transition sections in this direction. The radii of the transition sections of the bridging sections in the transition to the contact section connected to the lower sheet or to the upper sheet can be different, for example in order to simplify the production process.
The functionality of the floor sandwich construction can be adjusted depending on the inclination of the bridging sections as relates to the planar extension of the lower or upper sheet. If the bridging sections border at right angles to the lower or upper sheet or only deviate therefrom by a few angular degrees, the floor sandwich construction is stiffer against loads in the direction of the height thereof, compared to a design in which the bridging sections form a significantly smaller angle with the two sheets. Especially in the latter case, the bridging sections can be used for energy absorption. In particular, if the structural sheet is structured by support projections, energy is absorbed equally when the support projections are arranged according to a grid, regardless of the direction of action. In such a case, a material suitable for this purpose will be used to design the structural sheet.
As has already been pointed out, the contact sections are planar, thus connected to the upper and lower sheet with at least a section of the extension thereof in the width direction and over the length thereof continuously or via several or a plurality of connection points spaced apart from each other. In the sections of the upper and lower sheets where the contact sections of the structural sheet are connected, the upper and lower sheets are reinforced due to the greater cumulative material thickness. A hollow profile constructed in a shell structure, typically with an approximately rectangular cross-sectional area, is provided in the remaining sections.
Due to the transition sections pointing in the distance direction compared to the upper and lower sheet, an increased moment of resistance in the transverse direction as relates to the profiling direction of the structural sheet is designed to be especially stiff, due to the structuring, against a force acting from below. The connection of the contact sections to a sheet suppresses sliding movements between the contact sections and the respective sheet, which is why this floor has a particular rigidity also in the transverse direction as relates to the longitudinal extension of the contact sections of the structural sheet.
In a preferred embodiment, the contact sections are connected to the respective adjacent upper or lower sheet in the cross-section of the contact sections, over the entire width thereof or over as much of the width thereof as possible, in a manner resistant to shear, pressure, and tension.
In a further embodiment, the first contact sections of the structural sheet, which are connected to the lower sheet, are glued to the latter, whereas the second contact sections are soldered to the upper sheet. The material connection between the structural sheet and the upper and lower sheet results in an even distribution of force. In addition, the adhesive layer can provide a thermal insulation effect between the lower sheet and the structural sheet.
In the embodiment according to the invention, the hollow chambers formed by a structural sheet with a wavy cross-sectional profile, the contact sections of which follow the longitudinal or transverse extension of the floor, and by the upper sheet are used as temperature-control channels for conducting a fluid, typically for cooling the battery modules located in the battery housing. For this purpose, the end-side openings of the channels are connected to one another and connected to a coolant circuit. It is advantageous to use these hollow chambers, which are already present due to the special sandwich construction, since the battery modules typically rest on the upper sheet. Due to the course of the structural sheet, only a small material thickness thereof is required, so that the temperature-control channel arrangement formed by the structural sheet and the upper sheet has only a low heat-storing mass and is therefore especially effective.
If the structuring of the structural sheet is provided by a wavy profile, the contact sections of which follow the longitudinal extension of the floor, the end-side openings of the hollow chambers formed thereby can open into a common collector on each side of the floor. Moreover, it is possible to interconnect several individual hollow chambers and to connect them to a corresponding number of further channels by means of a deflection collector. In another embodiment, two adjacent hollow chambers are connected to each other. In this way, the temperature-control fluid flows into a hollow chamber at a distal end from a hollow chamber adjacent on one side and flows out at its other distal end into a hollow chamber adjacent on the other side, resulting in a meandering temperature-control line.
For temperature control, it is not absolutely necessary for all of the hollow chambers formed by the structural sheet and the upper sheet to be used as fluid channels. It is quite possible that only a part of the available hollow chambers is used for the intended temperature control.
The embodiment of a floor sandwich construction, in which the first contact section of the structural sheet is glued to the lower sheet and the second contact section of the structural sheet is soldered to the upper sheet, is especially effective for temperature control of the battery housing interior. On the one hand, soldering the upper sheet to the structural sheet results in especially good heat transfer between the sheets forming the hollow chambers, while, on the other hand, heat insulation is provided by the adhesive between the structural sheet and the lower sheet.
In a further embodiment, the upper sheet is thinner than the lower sheet. This design of the floor ensures that local deformations of the lower sheet, such as indentations, are avoided. Due to the sandwich construction, however, it is not necessary for the upper sheet to be correspondingly thick. An upper sheet that is thinner in terms of its thickness is advantageous in the case of temperature control of the floor.
In a further embodiment, it is provided that, in the cross-section of the structural sheet, the contact sections that are connected to the upper sheet have a smaller width than the contact sections with which the structural sheet is connected to the lower sheet. The free cross-sectional area of the hollow channels delimited by the upper sheet is then correspondingly larger, which in tuna is favorable in the case of temperature control of the floor.
The distance between the upper sheet and the lower sheet is preferably less than the width of the contact sections of the structural sheet. Typically, the transition sections are shorter than the critical buckling length according to Euler, with a buckling length factor of 0.5 being assumed (the element to be buckled is clamped on both sides). The critical buckling length according to Euler is decisive as to whether or not this buckling occurs when the transition sections are loaded with a predetermined force. One skilled in the art is sufficiently familiar with Euler's buckling cases such that detailed explanations are not necessary at this point.
In another embodiment, the bridging sections of the structural sheet are longer than the critical buckling length of same. In addition, it can be provided that the structural sheet is made of a crash alloy, such as a special aluminum alloy. In this way, a crash element is formed by the floor of the battery housing, with the transition sections being deformed in the event of a crash and thus being able to handle or absorb energy.
The invention is described on the basis of an exemplary embodiment with reference to the appended figures. The following is shown:
A structural sheet 8 is connected between the two sheets 6, 7. The two sheets 6, 7 are spaced apart from one another by the structural sheet 8. The structural sheet 8 is connected to both sheets 6, 7 in a manner resistant to shear, pressure, and tension. The structural sheet 8 is profiled in a meandering manner by means of U-shaped sections which are open toward the other side in an alternating manner. In its cross-sectional course shown in
The bridging sections 10, 12 connect the contact sections 9, 11, 9′ in the distance direction. For this purpose, they are arranged at right angles to the contact sections 9, 11. The first bridging section 10 is connected to the contact sections 9, 11, and the second bridging section 12 is connected to the second contact section 11 and first contact section 9′ of the following sequence of structural sections.
The bridging sections 10, 12 transition into the contact sections 9, 9′, 11 with a radius 14, 15, 16, 17 in each case. The radii 14, 15, 16, 17 are part of the bridging sections 10, 12 and are formed by the respective end sections of the bridging sections 10, 12. In the exemplary embodiment shown, there is a short, straight middle piece arranged at right angles to the sheets 6, 7, between radii 14, 15 or 16, 17, respectively, which are opposite one another in the thickness extension. This middle piece is arranged at right angles to the sheets 6, 7. The radii 14, 17 in the transition sections of the bridging sections 10, 12, which connect to the first contact sections 9, 9′, are designed with a larger radius than the radii 15, 16 with which the bridging sections 10, 12 adjoin the first contact sections 11.
The distance D between the upper sheet 7 and the lower sheet 6 is smaller than the smaller of the two different widths B1, B2 of the contact sections 9, 11. In the exemplary embodiment shown, the distance D corresponds to approximately half of width B1 of contact sections 11 and approximately one-third of width B2 of contact sections 9. This achieves a sandwich construction that is especially resistant to buckling.
In this exemplary embodiment, the hollow chambers 18, 18′ (
The hollow space formed between the upper sheet 7.1 and the structural sheet 8.1 can be used to conduct a temperature-control fluid. The temperature-control medium flows around the support projections 22.
In this embodiment, too, the structural sheet 8.2 is connected to the lower sheet 6.2 by adhesive 13.1. The structural sheet 8.2 is connected to the upper sheet 7.2 with a soldered joint. This takes place over the entire width of the respective contact sections 9.2, 9.2′, 11.2 resting against the sheets 6.2, 7.2, as has already been described for the exemplary embodiment in
The invention has been described on the basis of an exemplary embodiment. Without departing from the scope of protection, described by the claims, numerous further embodiments for implementing the concept of the invention are apparent to one skilled in the art, without these having to be explained in more detail at this juncture.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2019 132 450.5 | Nov 2019 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/083586 | 11/27/2020 | WO |
