BATTERY CABINETS

Description

[0001] The present invention relates to a battery box for a traction battery, as used to hold traction batteries in vehicles.

[0002] Battery boxes, also called battery cases, for traction batteries typically consist of two interconnected housing sections: a lower section in the form of a tray and an upper section in the form of a lid. Both housing sections are joined together and enclose the traction battery. The traction battery itself typically consists of a large number of individual battery cells (battery modules) arranged side by side and / or one above the other.

[0003] A particular problem with traction batteries is the risk of thermal runaway, i.e. thermal propagation from cell to cell, from defective cells and thus extreme short-term heating of the battery box, which can lead to flames penetrating through the battery box to the outside.

[0004] Therefore, high-voltage battery boxes, in particular, are usually lined with high-temperature-resistant materials. However, such materials typically offer little or no mechanical protection. Furthermore, they are difficult to maintain in a 3D shape, so the protective effect diminishes over time under the mechanical stress on the battery box during vehicle operation.

[0005] DE 10 2009 028 920 A1 discloses a rechargeable battery comprising a plurality of battery elements arranged next to one another and at least one thermal insulation means, wherein the at least one thermal insulation means is arranged between two adjacently arranged battery elements for reducing heat transport between the adjacent battery elements.

[0006] DE 10 2010 013 150 A1 discloses a device for thermally insulating at least one vehicle battery. The device comprises at least one first housing for accommodating the at least one vehicle battery. The first housing comprises at least one base part, at least one side part, and at least one top part. At least one spacer is arranged on the base part. The at least one vehicle battery is arranged at a distance from an inner surface of the base part, from an inner surface of the at least one side part, and from an inner surface of the at least one top part by means of the at least one spacer.

[0007] US 5,084,313 A shows an insulating material with a sequence of thin reflective foils and thin insulating layers.

[0008] EP 2 610 943 A1 discloses a battery with a housing. A pressurized insulation layer is arranged between the battery cell and the housing cover.

[0009] DE 20 2012 007 545 U1 discloses a heat shield for shielding hot areas with a housing having at least two metallic layers which are connected to one another at their edges in a form-fitting and / or material-fitting and / or force-fitting manner, at least in sections, and an insulating layer made of compressed insulating material arranged at least in sections between the two metallic layers.

[0010] DE 10 2016 008 222 A1 discloses a traction battery with a plurality of interconnected battery cells, each having positive and negative electrode plates arranged alternately in a cell housing, and with a plurality of battery trays, each serving to accommodate a plurality of battery cells, wherein each battery tray is electrolyte-resistant and leak-proof, and with a battery box accommodating the battery trays, wherein adjacent battery trays are arranged at a distance from one another while leaving a gap.

[0011] The object of the present invention is therefore to provide a battery box which prevents or at least significantly delays the penetration of flames and particles from the battery box to the outside, is inexpensive to manufacture and also ensures the safety of the battery box in the long term.

[0012] This object is achieved by the battery box according to claim 1. Advantageous developments of the battery box according to the invention are given in the dependent claims.

[0013] The battery box according to the invention, as is customary in the prior art, has a bottom side, usually designed as a tray and occasionally referred to as such below, and a top side, usually designed as a lid and occasionally referred to as such below. A plurality of battery modules are arranged in the battery box.

[0014] The battery box according to the invention is now designed in such a way that it has a high temperature resistance with a high mechanical protection and reliably delays or completely prevents the penetration of flames from the battery box to the outside.

[0015] For this purpose, a flat shielding element with at least two layers is arranged in the battery box between the battery modules and the upper side, i.e. the lid. Such a shielding element can also be arranged between two battery modules for shielding purposes. The battery modules can be arranged horizontally next to one another, vertically next to one another or otherwise adjacent to one another in the battery box. According to the invention, the shielding element has a first outer metallic layer and a second outer metallic layer, for example made of a metal sheet, wherein at least one metallic layer, referred to below as the second outer layer, of the outer layers consists of or comprises a steel with a melting point T s ≥ 1000°C, for example a steel sheet. The shielding element is arranged such that the second outer layer made of steel is arranged adjacent to a battery module.

[0016] The two-layer design effectively shields the area surrounding the battery module on the opposite side of the shielding element from high temperatures, starting with the shielded battery module. If a shielding element is located between two battery modules, heat transfer from one battery module to the neighboring battery module is significantly delayed or prevented. This prevents overheating from one battery module (a so-called "thermal runaway") from spreading to the neighboring battery module.

[0017] Because the shielding element is positioned between the battery modules and the top of the battery box (the cover), the spread of heat to the battery cover and from there into the vehicle can be prevented or at least significantly delayed. Because the second outer layer adjacent to the shielded battery module is made of or has a steel with a melting point T s ≥ 1000°C, the shielding element itself is highly temperature-resistant.

[0018] The first layer, which lies opposite the second outer layer, is made of steel, in particular sheet steel. The first outer layer, which is adjacent to the top of the battery box and is itself shielded from the battery modules by the second outer layer, can also be made of a lightweight material such as aluminum.

[0019] This provides a number of advantages in addition to increasing the temperature resistance of a battery box.

[0020] Firstly, the two-layer shielding element provides very high thermal shielding of a battery module(s) from its surroundings, e.g., another battery module or the top of a battery box, and thus from a vehicle. During normal operation, the shielding element's excellent thermal insulation properties effectively maintain and operate the battery modules within their nominal temperature range.

[0021] The use of metallic layers for the shielding element allows the shielding element to be perfectly adapted to the 3D shape of the top side of the battery box, i.e., the lid / hood. Since the shielding element is self-supporting, it can also be easily installed inside the hood. Using aluminum sheet for the first outer layer significantly reduces the weight of the shielding element. Nevertheless, it provides high thermal insulation both during normal operation and is resistant to flames or heating at high temperatures. Since very high temperatures of up to 1000°C and above can occur in the event of a thermal runaway of a battery cell, the second outer layer, which is thermally resistant even at higher temperatures, ensures that the entire battery box is resistant for some time, particularly advantageously for at least 5 minutes.The penetration of thermal runaway into the vehicle is therefore significantly delayed or prevented. The choice of metals as the material for the metallic layers also provides mechanical protection for the battery modules.

[0022] According to the invention, a stainless steel, such as 1.4301 steel, can be used for the second outer layer. It is also possible to use an aluminum-clad steel or a hot-dip aluminized steel for the second outer layer.

[0023] Particularly, but not exclusively, in the case of stacked (i.e., vertically adjacent) battery modules, the first and / or second outer metallic layer, preferably both, are made of stainless steel. These two stainless steel layers protect the shielding element, an adjacent battery module, and each other in the event that one of the adjacent battery modules is defective and overheats abnormally. Furthermore, the stainless steel layers can easily support the weight of one or more battery modules arranged above.

[0024] If the first outer layer is also made of steel, the same materials can be used for the second outer layer. However, if the first outer layer is made of aluminum, aluminum sheets of different thicknesses can be used. Typically, the aluminum sheet of the first outer layer is thicker than a steel sheet of the second outer layer. For the first layer, thicknesses D1 are used as the maximum thickness of the layer or as the average thickness of the layer of 0.1 mm ≤ D1 ≤ 2.0 mm, advantageously 0.3 mm ≤ D1 ≤ 0.6 mm. The second layer, which consists of or comprises a steel sheet, has a thickness as the maximum thickness of the layer or as the average thickness of the layer D2 of 0.1 mm ≤ D2 ≤ 1.0 mm, advantageously 0.1 mm ≤ D2 ≤ 0.3 mm, in particular a thickness of D2 = 0.15 mm.

[0025] One or both of the first outer layer and the second outer layer can be perforated, in particular microperforated, punched, or dimpled. This makes it possible, for example, to further improve the sound insulation provided by the shielding element and achieve further weight reduction.

[0026] It is not absolutely necessary for there to be an additional insulation layer between the first outer layer and the second outer layer. However, it is advantageous if such an insulation layer is inserted between the two outer layers. For this insulation layer, it is advantageous if it consists of or contains a material that is stable up to at least 600°C. This is fulfilled, for example, by fiber materials such as glass fiber, rock wool, silicate fibers or even mica. Aluminum-coated glass fibers are also suitable as the material for the insulation layer. Furthermore, appropriately treated cardboard containing fillers, binders and other components can also be used as an insulation layer. Cardboard such as that commonly used in heat shields for internal combustion engines can be used here.

[0027] The insulation layer does not need to be self-supporting, so that a binder-free insulation layer can be used. The mechanical stability of the insulation layer is ensured by its embedding between the two outer layers. This at least three-layer structure of the shielding element also prevents the insulation layer from being mechanically destroyed during vehicle operation and from being worn away by the shielding element. While the individual fibers and the like of the insulation layer may become detached or broken during vehicle operation, they remain in place because they are sufficiently enclosed between the two outer metallic layers and continue to contribute to the insulating effect of the shielding element.

[0028] One or both of the outer layers can also be dimpled and / or perforated, or have any other embossed structures, such as beads and the like, or even a combination of different structures. Such surface structuring keeps the respective outer layer spaced from the adjacent component, such as the battery box cover, so that an additional thermally insulating air gap can form between them.

[0029] One or both outer layers can also be perforated or punched to create through-holes, for example, in the form of a tanged metal sheet. The insulation layer can also extend through these through-holes and thus be anchored to the respective layer. Such a layer can also be embedded, at least in part, in the material of the insulation layer, e.g., as a tanged metal sheet embedded in an insulation layer made of NBR-bonded mica.

[0030] Because the shielding element can be preformed in a 3D shape to fit the cover or the battery module, it is not necessary to firmly connect the shielding element to an adjacent component, for example, by screwing, riveting, clamping, etc. Often, it is sufficient to simply insert the shielding element loosely into the battery box, as its 3D shape holds it in place.

[0031] The battery box according to the invention is thus effectively improved with regard to mechanical stress and its thermal insulation properties by the shielding element according to the invention, which is adapted to the requirements of a battery box of a traction battery or to the requirements of traction batteries. This improvement is realized particularly cost-effectively and with minimal additional weight.

[0032] Some examples of battery boxes according to the invention are given below. The same and similar reference numerals are used throughout for identical and similar components, so that repetition and description are omitted where appropriate. The following examples describe a variety of improvements and developments of the present invention, each of which can further develop the present invention on its own or can be combined with other further developments of the same example or other examples.

[0033] It shows Fig. 1 in the three partial images A, B and C the arrangement and construction of a battery box according to the invention; Fig. 2 the arrangement of battery cells in a battery box; Fig. 3 a cross section through a shielding element of a battery box according to the invention; Figs. 4-6 cross sections through further shielding elements of battery boxes according to the invention; Fig. 7 examples of different materials for use as layers in shielding elements of battery boxes according to the invention; Fig. 8 an arrangement of battery cells in a battery box one above the other; Fig. 9 a cross section through the Fig. 8 used shielding element; and Fig. 10 a cross-section through another shielding element.

[0034] Fig. 1 shows a vehicle 1 with a battery box 2 mounted on an underbody 5 of a vehicle.

[0035] Fig. 1A shows vehicle 1, while Fig. 1B und 1C show a perspective view in transparent form or a plan view of a cross-section through the battery box.

[0036] According to sub-figures 1A, 1B, and 1C, the battery box 2 has a bottom in the form of a tray 3 and a top in the form of a battery cover 4. Both the tray 3 and the cover 4 have flanges 3a, 4a and 3a', 4a', respectively, which lie on top of one another in pairs and at which the tray 3 is connected to the cover 4. A shielding element 10 is arranged on the inside of the cover 4, which largely lines the top of the cover 4 and has a 3D shape corresponding to the 3D shape of the cover 4.

[0037] Fig. 2 shows a further arrangement according to the invention in which shielding elements 10a, 10b, 10c are arranged between individual battery cells 6a, 6b, 6c and 6d of a traction battery.

[0038] In Fig. 1 Thus, a shielding of the interior of a battery box, in which a traction battery (not shown) is arranged, is shown upwards towards the interior of the vehicle 1, while in Fig. 2 a thermal shield between individual battery cells of a traction battery, which is installed in a corresponding battery box as in Fig. 1 shown arranged as shown.

[0039] Fig. 3 shows a cross-sectional view of a shielding element 10 of a battery box according to the invention. Here, as in the following figures, the shielding element 10 can be used both for shielding between a traction battery and a cover 4 of a battery box 2 and for shielding between two battery cells within a battery box 2.

[0040] In Fig. 3 The shielding element 10 comprises a first layer 11 made of a 0.4 mm thick aluminum sheet, a second layer 12 made of a 0.2 mm thick stainless steel sheet, and a third layer 13 as an insulating layer. The third layer 13 is made of mica.

[0041] The two layers 11 and 12 are configured at their edges such that layer 11 has a flange 11a and layer 12 has a flange 12a, which lie flat against one another. The flange 12a encompasses the flange 11a and thus completely seals the shielding element 10. As a result, the mica of layer 13 is completely enclosed between layers 11 and 12 and cannot escape the shielding element 10 even if its own internal mechanical stability is lost.

[0042] Fig. 4 shows a further example of a shielding element 10 for use in battery boxes according to the invention.

[0043] The shielding element 10 is designed similarly to that in Fig. 3 . Now, however, the first layer 11 is made of a 0.4 mm thick aluminum sheet, and the second layer 12 is made of a 0.2 mm thick perforated stainless steel sheet or a stainless steel mesh or a stainless steel grid of the same thickness. The second layer 12 thus has openings 15a to 15i, as well as further openings (not shown) that are regularly spaced and allow heat and sound to enter the third layer 13 through the openings 15a to 15i. The third layer 13 is a glass mat, for example made of ECR ​​glass or silicate glass fibers, with a basis weight of, for example, 650 g / m² and a thickness of 4 mm at its thickest point.

[0044] Layer 11 is made of aluminum sheet, while layer 12 is made of stainless steel and is particularly thermally resistant as the flame-exposed side.

[0045] In the design of the Fig. 4 the second layer 12 now has a flange 12a and the first layer 11 has a flange 11a which surrounds the flange 12a and thus mechanically connects the first layer 11 to the second layer 12;

[0046] Fig. 5 shows a further shielding element of a battery box according to the invention, which is designed similarly to the one in Fig. 4 . Deviating from Fig. 4 The first layer is made of aluminum, hot-dip aluminized steel (FAL), aluminum-clad steel (ALP), or stainless steel. The second layer consists of a 0.2 mm thick stainless steel sheet.

[0047] On the side of the insulation layer 13 facing the second layer 12, a further layer 14 made of expanded metal or a dimpled metal layer is arranged. This serves to further enhance the protection against thermal breakdowns and to mechanically reinforce the shielding element.

[0048] Fig. 6 shows another example of a shielding element for a battery box according to the invention corresponding to that in Fig. 3 .

[0049] While in Fig. 3 the flange 12a surrounds the flange 11a in the direction of the side facing the battery box cover, is in Fig. 6 the first layer 11 is provided with a flange 11a and the second layer 12 with a flange 12a, wherein the flange 11a surrounds the flange 12a in the direction of the inside of the battery box.

[0050] Fig. 7 shows examples of various special and suitable materials for the layers 11, 12, 13 and 14 in the previous examples of the Figuren 1 bis 6 . Fig. 7A shows a mesh or grid, for example made of stainless steel, Fig. 7B shows a perforated sheet and Fig. 7C an expanded metal, which can be used for each of these layers, but in particular for the second layer 12 and the additional intermediate layer 14.

[0051] Fig. 8 shows a cross-section of a battery box 2. Two battery modules 16 are arranged vertically one above the other, between which a shielding element 10 is arranged.

[0052] Fig. 9 shows the cross-sectional structure of this shielding element 10. It comprises a first outer metallic layer 11 made of stainless steel and a second outer metallic layer 12 made of aluminum. Layer 11 is flanged around the outer edge of layer 12 at its edge, thus connecting it to the outer edge. An insulating layer 13 made of glass fibers is provided between layers 11 and 12, with the glass fibers being vapor-coated with aluminum.

[0053] Fig. 10 shows in the partial figures 10a and 10b an alternative design of a shielding element, for example the shielding element in Fig. 9The first outer layer 11 is again made of stainless steel and surrounds a second outer layer 12 at its outer edge. Layer 12 is a tanged sheet made of stainless steel. Layer 12 is at least partially embedded in an insulating layer 13 made of mica particles coated with NBR (acrylonitrile butadiene rubber).

Claims

1. A battery box (2) having a traction battery with a plurality of battery modules (16), wherein the battery box (2) has a lower side and an upper side as well as a circumferential edge region between the upper side and the lower side, wherein the plurality of battery modules (16) of the traction battery are arranged in the battery box (2), characterised in that an at least two-layer flat shielding element is arranged between the battery modules (16) and the upper side, which shielding element comprises a first outer metallic layer (11), which is arranged adjacent to the upper side of the battery box (2) and consists of aluminium or of steel, and a second outer metallic layer (12), which is spaced apart from the first outer layer (11) at least in regions and consists of a metal with a melting point Ts ≥ 1000°C, and which is arranged adjacent to a battery module (16), wherein the first layer (11) has a thickness D1 of 0.1 mm ≤ D1 ≤ 2.0 mm, and the second layer (12) has a thickness D2 of 0.1 mm ≤ D2 ≤ 1 mm.

2. The battery box (2) according to the preceding claim, characterised in that the first outer layer (11) and / or the second outer layer (12) consists of or essentially contains a metal sheet or other metallic material.

3. The battery box (2) according to any one of the preceding claims, characterised in that the first layer (11) and / or the second layer (12) is perforated, in particular microperforated, nubbed and / or holed.

4. The battery box (1) according to any one of the preceding claims, characterised in that an insulating layer (13) is arranged between the two outer layers 11, 12).

5. The battery box (2) according to the preceding claim, characterised in that the insulating layer (13) contains or consists of a material which is stable up to at least 600°C, in particular a fibrous material such as glass fibre, e.g. glass fibres vapour-deposited with aluminium, rock wool, silicate fibres and the like, mica and / or a cardboard containing fillers and binders.

6. The battery box (2) according to any one of the preceding claims, characterised in that the insulation layer (13) is not self-supporting, and in particular is free of binding agents.

7. The battery box (2) according to any one of the preceding claims, characterised in that the metal of the first and / or the second outer layer (11, 12) is or comprises a stainless steel or a hot-dip aluminized steel or an aluminium-clad steel.

8. The battery box (2) according to any one of the preceding claims, characterised in that the first layer (11) has a thickness D1 of 0.3 mm ≤ D1 ≤ 0.6 mm.

9. The battery box (2) according to any one of the preceding claims, characterised in that the second layer (12) has a thickness D2 of 0.1 mm ≤ D2 ≤ 0.3 mm, in particular D2 = 0.15 mm or D2 = 0.2 mm.

10. The battery box (2) according to any one of the preceding claims, characterised in that the insulation layer (13) has a maximum or average thickness D3 of 0.5 mm ≤ D3 ≤ 10 mm, in particular 0.5 mm ≤ D3 ≤ 3 mm, in particular D3 = 0.7 mm or D3=3 mm.

11. The battery box (2) according to any one of the preceding claims, characterised in that the first layer (11) and the second layer (12) are crimped, clinched and / or welded together along their outer edges, at least in certain regions.

12. The battery box (2) according to any one of the preceding claims, characterised in that the shielding element (10a, 10b, 10c) is loose or is clamped in the battery box (2).

13. The battery box (2) according to any one of the preceding claims, characterised in that the shielding element (10a, 10b, 10c) is fastened to the cover (4) and / or the trough (3) of the battery box (2).