VEHICLE WITH A HIGH-VOLTAGE STORAGE SYSTEM

Description

[0001] The present invention relates to a vehicle with a high-voltage storage device according to the preamble of patent claim 1.

[0002] Such a vehicle is known from JP 2012 113 896 A. The technical background of the invention includes US 2013 / 004813 A1 and CN 107 507 937 A.

[0003] High-voltage storage units in electric or hybrid vehicles, such as the BMW i3, feature a high-voltage storage housing with several so-called "cell modules" arranged within it. Each cell module consists of several battery cells arranged one behind the other in a row, which are electrically interconnected. In the BMW i3, the housing in which the individual battery cells are arranged is a relatively rigid aluminum casing, which is closed "at the top," i.e., toward the passenger compartment, by a screwed-on cover.

[0004] The individual battery cells of the BMW i3 each have a substantially cuboid-shaped battery cell housing. When the battery cells are in proper condition, the battery cell housing is liquid- and gas-tight, meaning nothing can escape from the interior of the battery cell housing.

[0005] Should battery cells be damaged, for example, in an extremely serious accident and / or a short circuit occurs in or between individual battery cells and the interior of a battery cell heats up to an unacceptable level, an "emergency venting" of the affected battery cells must be possible. For this purpose, battery cell housings usually have an emergency venting opening, which can be designed, for example, as a predetermined breaking point, which opens when a predetermined internal cell pressure is exceeded and allows gas to escape from the interior of the battery cell to the outside. In extreme cases, such as massive damage to individual battery cells, the escaping gas can ignite in very unfavorable situations. However, escape into the environment or into the vehicle's passenger compartment is reliably prevented by the fact that the battery cells are additionally enclosed by the housing of the high-voltage storage unit.

[0006] The object of the invention is to create a vehicle with a high-voltage storage device which, compared to vehicles with conventional high-voltage storage devices, offers even greater safety with regard to possible fire hazards.

[0007] This object is achieved by the features of patent claim 1. Advantageous embodiments and further developments of the invention can be found in the subclaims.

[0008] The starting point of the invention is the consideration that in the event of extreme mechanical damage to individual battery cells and / or cell-internal short circuits, very hot, burning gas should be able to escape from the interior of individual battery cells into the interior of the high-voltage storage housing via the emergency degassing openings of the battery cell housing.

[0009] The basic principle of the invention is to make the high-voltage storage housing more locally thermally resistant, at least in those areas where the emergency venting openings of the battery cells are located. In principle, the entire high-voltage storage housing could be made fire-resistant, e.g., by selecting a correspondingly fire-resistant material, such as steel, and sufficiently thick walls. However, this is not absolutely necessary for safety reasons and would, moreover, result in a significant increase in the weight of the high-voltage storage housing. Accordingly, the invention aims to reinforce the housing of the high-voltage storage device (only) in those areas that are subject to particularly high thermal stress in an extreme case, i.e., during a so-called "thermal event."

[0010] The starting point of the invention is a vehicle with a high-voltage storage device comprising a housing and at least one battery cell arranged within the housing. Instead of a single battery cell, several or a plurality of battery cells can, of course, be arranged within the housing, which can be interconnected in "packs" to form so-called "cell modules."

[0011] The at least one battery cell arranged in the housing of the high-voltage storage device has an emergency vent opening that opens at a predetermined internal cell pressure, through which hot or burning gas can escape from the interior of the battery cell housing into the housing of the high-voltage storage device in the event of a malfunction or damage to the battery cell. The emergency vent opening of the battery cell housing faces a wall of the housing of the high-voltage storage device, against which hot or burning gas flows (immediately) in the event of a malfunction or damage to the battery cell.

[0012] As already mentioned above, the core of the invention is that the wall of the high-voltage storage device is designed to be locally more thermally resistant in the area in which the emergency venting opening is arranged and in the event of a malfunction or damage to the battery cell, hot or burning gas flows out of the battery cell housing, than in areas of the wall spaced apart from it.

[0013] The wall of the high-voltage storage unit's housing is therefore only locally thermally reinforced or made more thermally resistant. "Local" in this context means the area(s) where hot or burning gas escaping from the interior of the battery cell housing(s) directly impacts the wall of the high-voltage storage unit's housing, similar to the burning gas jet from a welding torch.

[0014] The wall of the housing of the high-voltage storage unit consists of an aluminum sheet which is designed to be locally more thermally resistant in the area in which the at least one emergency venting opening is located and in the event of a malfunction or damage to the battery cell, hot or burning gas flows out of the battery cell housing.

[0015] Outside the scope of the invention, the wall of the housing of the high-voltage storage device can also consist entirely or at least in part of a plastic material (or a fiber-reinforced plastic material), which is designed to be locally more thermally resistant in the area in which the at least one emergency venting opening is arranged and in the event of a malfunction or damage to the battery cell, hot or burning gas flows out of the battery cell housing.

[0016] As already mentioned above, it can be provided that, when the at least one battery cell is in proper working order, the interior of the battery cell is sealed gas-tight by the emergency vent. The emergency vent can be formed, for example, by a predetermined breaking point provided in the battery cell housing, which only opens, or is "pressed open," or burst open, when a predetermined pressure inside the battery cell housing is exceeded.

[0017] In principle, the entire housing of the high-voltage storage device can be provided with an additional thermally resistant layer. One concept of the invention is that the wall of the high-voltage storage device has at least one more thermally resistant layer, i.e., at least one additional thermally resistant layer, in the area of ​​the at least one emergency venting opening than in spaced-apart areas of the wall.

[0018] For example, it can be provided that the one thermally resistant layer or the several thermally resistant layers which locally thermally reinforce or reinforce the wall of the high-voltage storage housing have or have a total layer thickness of at least 0.1 mm.

[0019] In order to locally reinforce the wall of the housing of the high-voltage storage unit, the invention provides that the wall in the area of ​​at least one emergency degassing opening is coated with a thermally resistant coating. "Thermally resistant" in this context means that a coating is used that is thermally resistant at least up to a specified minimum temperature of, for example, 1000°C, 1100°C, 1200°C, or 1300°C. Activation of the coating by the heat generated during emergency degassing can be utilized as a positive effect. For example, the coating does not need to be baked when applied to the housing (especially with ceramic coatings), but is simply painted. Sufficient adhesion for normal operation is achieved through the normal drying of the coating. The heat of the emergency degassing then activates / bakes the coating, allowing it to achieve its full "thermal resistance."The coating layer can therefore be an intumescent layer ("insulating layer"). Intumescent materials increase in volume and decrease in density when exposed to heat. The layer can be designed to "char" under heat, expanding and thus providing thermal insulation.

[0020] According to the invention, the wall of the housing of the high-voltage storage unit, in the area of ​​the at least one emergency venting opening, has at least one thermally resistant layer containing phyllosilicates or mica. For example, a layer or plate known commercially as a "mica" layer or "mica" plate can be used as the layer containing phyllosilicates or mica.

[0021] The at least one thermally resistant layer can be glued, screwed, riveted, or otherwise connected to the wall of the high-voltage storage unit housing. The thermally resistant layer can be applied directly to the wall of the high-voltage storage unit housing or can be arranged at a certain distance of a few mm from the wall of the high-voltage storage unit housing using spacer elements. If the thermally resistant layer is glued to the wall of the high-voltage storage unit housing, an adhesive is preferably used that is thermally resistant up to a temperature of at least 600°C and does not burn up to a temperature of 1200°C.

[0022] Alternatively or additionally, it can be provided that the at least one thermally resistant layer is completely or partially overmolded and / or pressed with material from which the wall is made (e.g. aluminum, die-cast aluminum).

[0023] According to a further development of the invention, it is provided that the at least one battery cell arranged in the interior of the housing of the high-voltage storage device is arranged such that the emergency degassing opening of the at least one battery cell is assigned to an upper wall or a cover of the high-voltage storage device with respect to the direction of gravity.

[0024] Furthermore, it can be provided that the wall of the housing of the high-voltage storage unit is designed to be more thermally resistant on its side facing the emergency venting opening, i.e., on an inner side of the housing, than in areas of the wall spaced apart from it. Preferably, the "local thermal reinforcement" is therefore applied to the inner side of the wall of the high-voltage storage unit. However, this is not mandatory. In principle, the wall of the high-voltage storage unit could also be locally thermally reinforced on its side facing away from the interior of the high-voltage storage unit housing, i.e., on the outer side of the wall of the high-voltage storage unit housing.

[0025] As already mentioned above, several or a plurality of battery cells, each with an emergency venting opening, are preferably arranged in the housing of the high-voltage storage device. Preferably, all battery cells are arranged so that their respective emergency venting openings face the same wall of the housing (e.g., the housing cover). Accordingly, it can be provided that the wall in the area of ​​all emergency venting openings is designed to be more thermally resistant than in spaced-apart areas of the inner wall of the housing of the high-voltage storage device.

[0026] For example, it can be provided that the at least one thermally resistant layer with which the wall of the housing of the high-voltage storage device is locally thermally reinforced consists of a material that does not melt or burn at least up to a temperature of 1000°C or 1100°C or 1200°C or 1300°C.

[0027] Furthermore, it can be provided that the thermally resistant region of the wall withstands a temperature of up to 2000°C, in particular at a temperature of up to 1600°C, for at least a period of 0.5 minutes without being perforated or melting.

[0028] The at least one thermally resistant layer can, in particular, be a so-called "SMC" (sheet-molded compound) layer, i.e., a layer composed of several individual layers. One or more of these layers can be plastic layers reinforced with glass fibers and / or mineral fibers, for example.

[0029] The invention is explained in more detail below in conjunction with the drawings. They show: Figure 1a shows a schematic plan view of a high-voltage storage housing according to the invention; Figure 1b shows a schematic cross-section through a high-voltage storage housing according to the invention; Figure 1c shows a part of a wall of a high-voltage storage housing that is locally reinforced by a thermally resistant layer.

[0030] Figure 1a shows a schematic top view of a high-voltage storage device 1 having a housing 2. Two cell modules 3a, 3b are arranged in the housing of the high-voltage storage device 1. Each of the two cell modules 3a, 3b consists of several individual battery cells arranged one behind the other (not shown in detail), which are electrically interconnected. Each of the battery cells has a battery cell housing.

[0031] On the upper sides (oriented outward from the plane of the drawing) of the battery cell housings, the individual battery cell housings each have an emergency venting opening 4a, 4b, 4c (cf. Figure 1b ). If the battery cells are in proper condition, the emergency vents are closed, meaning the battery cell housings are gas-tight, preventing any liquids or gases from escaping from the interior of the battery cell housings.

[0032] In the event of a malfunction or damage to individual battery cells, this can lead to internal cell short circuits, an increase in the internal cell pressure and the escape of flammable or burning gases from the interior of individual battery cells into the interior of the housing 2 of the high-voltage storage unit 1.

[0033] Should escaping gases ignite, very high temperatures may occur, particularly in the area of ​​the emergency venting openings 4a, 4b, 4c, i.e. in those areas where burning gases escape from the battery cells, similar to what happens with a burning gas jet from a welding device.

[0034] To avoid endangering people even in such extreme scenarios, it is important that the housing 2 of the high-voltage storage unit 1 is sufficiently thermally resistant. When burning gases escape from individual battery cells, the greatest thermal stresses occur in the area or immediate vicinity of the emergency vents. Just a few centimeters away from the emergency vents, the thermal stresses are already significantly lower.

[0035] In Figure 1bThe direction of gravity is indicated by an arrow 5. The housing 2 of the high-voltage storage device 1 has a base 2a, side walls 2b, 2c, and a cover 2d arranged on a top side of the housing 2. A thermally resistant layer 6a, 6b is arranged on an inner side of the cover 2d.

[0036] As from Figure 1a As can be seen, the thermally resistant layers 6a, 6b do not extend over the entire surface or inside of the cover 2d, but only over those areas in which the emergency degassing openings 4a, 4b, 4c of the battery cells (not shown in detail here) are arranged.

[0037] The thermally resistant layers 6a, 6b are therefore only provided where they are actually needed, i.e., where the greatest thermal loads occur during a thermal event. More widely spaced regions of the cover 2d or the side walls 2b, 2c, or the base 2a of the housing do not have such an additional thermally resistant layer. The thermally resistant layers 6a, 6b are therefore only arranged locally in the areas most exposed to thermal stress in the event of an accident or similar event. The thermally resistant layers are layers of phyllosilicates or mica and a correspondingly thermally resistant lacquer.

[0038] The thermally resistant layers 6a, 6b can in turn be constructed from several individual layers.

[0039] Figure 1cshows an embodiment in which a thermally resistant layer 6a is arranged on a cover 2d of a housing 2 (not shown in detail here) of a high-voltage storage device 1. The thermally resistant layer 6a has several through-openings, of which only a single through-opening 7 is shown here. Material of the cover 2d extends plug-like and thus in a form-fitting manner through the through-opening 7. A plug 2d' of the cover material projects over the through-hole 7 in a form-fitting manner, whereby the thermally resistant layer 6a is connected to the cover 2d in a form-fitting manner. The cover 2d is made of aluminum or a cast aluminum material.

[0040] The thermally resistant layer can thus be partially or completely overmolded or encapsulated with the material of the cover 2d. Alternatively, the thermally resistant layer 6a can also be glued, screwed, riveted, or otherwise connected to the cover 2d.

Claims

1. Vehicle with a high-voltage storage device (1), which • has a housing (2) and • at least one battery cell arranged in the housing (2), wherein the at least one battery cell has a battery cell housing with an emergency degassing opening (4a - 4c) that opens at a predetermined cell internal pressure, through which, in the event of a malfunction or damage to the battery cell, hot or burning gas can escape from the interior of the battery cell housing into the housing (2) of the high-voltage storage device (1), wherein the emergency degassing opening (4a - 4c) faces a wall (2d) of the housing (2) against which hot or burning gas flows in the event of a malfunction or damage to the battery cell, wherein • the wall (2d) of the housing (2) of the high-voltage storage device (1) in the area where the emergency degassing opening (4a - 4c) is arranged and where hot or burning gas flows out of the battery cell housing in the event of a malfunction or damage to the battery cell, is locally designed to be more thermally resistant than in areas spaced apart from it of the wall (2d), wherein the wall (2d) in the area of the at least one emergency degassing opening (4a - 4c) has at least one thermally resistant layer (6a) containing layer silicates or mica and wherein the wall (2d) in the area of the at least one emergency degassing opening (4a - 4c) is coated with a thermally resistant lacquer layer, and wherein the wall (2d) consists of aluminum sheet which, in the area where the emergency degassing opening (4a, 4c) is arranged and where hot or burning gas flows out of the battery cell housing in the event of a malfunction or damage to the battery cell, is locally designed to be more thermally resistant.

2. Vehicle according to claim 1, characterized in that the emergency degassing opening is gas-tightly sealed when the battery cell is in proper condition.

3. Vehicle according to one of claims 1 to 2, characterized in that the emergency degassing opening is formed by a predetermined breaking point that opens when a predetermined pressure in the interior of the battery cell housing is exceeded.

4. Vehicle according to one of claims 1 to 3, characterized in that the wall (2d) in the area of the at least one emergency degassing opening (4a - 4c) has at least one more thermally resistant layer (6a) than in areas spaced apart from it of the wall (2d).

5. Vehicle according to claim 4, characterized in that the at least one thermally resistant layer or the multiple thermally resistant layers have or has a total layer thickness of at least 0.1 mm.

6. Vehicle according to one of claims 1 to 5, characterized in that the at least one thermally resistant layer (6a) is adhesively bonded to the wall (2d).

7. Vehicle according to claim 6, characterized in that the adhesive is an adhesive that is resistant to at least a temperature of 600°C and does not burn up to a temperature of 1200°C.

8. Vehicle according to one of claims 1 to 7, characterized in that the at least one thermally resistant layer (6a) is screwed and / or riveted to the wall (2d).

9. Vehicle according to one of claims 1 to 8, characterized in that the at least one thermally resistant layer (6a) is partially or completely overmolded and / or overpressed with material from which the wall (2d) is made.

10. Vehicle according to one of claims 1 to 9, characterized in that the at least one battery cell is arranged such that the emergency degassing opening (4a - 4c) faces an upper wall (2d) or a lid of the high-voltage storage device (1) with respect to the direction (5) of gravity.

11. Vehicle according to one of claims 1 to 10, characterized in that the wall (2d) on its side facing the emergency degassing opening, which is an inner side of the housing (2), is designed to be more thermally resistant than in areas spaced apart from it of the wall (2d).

12. Vehicle according to one of claims 1 to 11, characterized in that several battery cells are arranged in the housing (2) of the high-voltage storage device (1), whose housings each have an emergency degassing opening.

13. Vehicle according to claim 12, characterized in that all battery cells are arranged such that their respective emergency degassing openings (4a - 4c) face the same wall (2d) of the housing (2).

14. Vehicle according to one of claims 12 or 13, characterized in that the wall (2d) in the area of all emergency degassing openings (4a - 4c) is designed to be more thermally resistant than in areas spaced apart from it of the wall (2d) of the housing (2).

15. Vehicle according to one of claims 1 to 14, characterized in that the at least one thermally resistant layer is made of a material that does not melt and does not burn at least up to a temperature of 1000°C or 1100°C or 1200°C or 1300°C.

16. Vehicle according to one of claims 1 to 15, characterized in that the more thermally resistant designed area (6a, 6b) of the wall (2d) can withstand a temperature of up to 2000°C, in particular a temperature of up to 1600°C, for at least a duration of 0.5 minutes without being perforated or burned.