Battery unit for vehicle

Abstract

The present disclosure relates to a battery unit for a vehicle. The battery cell includes a battery tray made of a composite material and defining an interior space configured for receiving a battery including one or more battery cells. In addition, the interior space is defined by a bottom wall and one or more side walls. In addition, the battery cell includes a top cover configured to close the battery tray, in which a cooling system for cooling the battery is integrated. The present disclosure further relates to a battery system and a vehicle comprising one or more battery cells.

Description

Technical Field

[0001] This application claims the benefit of European Patent Application No. 22382941.7 filed on October 6, 2022. The present disclosure relates to a battery cell for a vehicle. More specifically, the present disclosure relates to a battery cell comprising a battery tray made of a composite material and a top cover comprising a cooling system. The present disclosure further relates to a battery system comprising one or more battery cells and a vehicle comprising such a battery system. Background Art

[0002] Vehicles such as automobiles incorporate a structural framework designed to withstand all loads that the vehicle may experience during its lifetime. The structural framework or "body in white" (BIW) is also designed to withstand and absorb impacts in the event of, for example, a collision with another automobile. The structural framework is also designed to be as light as possible in order to reduce the emission of pollutants such as CO2 to the environment or to reduce electricity consumption in electric vehicles.

[0003] The structural framework or BIW of an automobile may include, for example, bumpers, pillars (e.g., A-pillars, B-pillars, C-pillars), side impact beams, and rocker panels. These and other structural members may have one or more regions having a generally U-shaped (also referred to as a "hat" shaped) cross-section. These structural members may be manufactured in a variety of ways and may be made of a variety of materials. For example, a rocker panel may be made of steel, particularly ultra-high strength steel (UHSS), and may be manufactured by press hardening.

[0004] Ultra-high strength steel (UHSS) exhibits optimized maximum strength per unit weight and favorable formability for the structural frame of a vehicle or at least its components in the automotive industry. In the present disclosure, UHSS may be considered to be a steel having a maximum tensile strength (after hot stamping) of at least 1000 MPa, preferably at most about 1500 MPa or at most 2000 MPa or more. An example of UHSS used in the automotive industry is a boron steel, such as 22MnB5 steel.

[0005] Machining components for vehicles may include forming sheet metal, in particular steel sheet, so as to give the sheet a desired shape. One method used in particular in the automotive industry is hot forming die quenching (HFDQ). In the HFDQ method, a steel blank is heated to above the austenitizing temperature, above Ac1 or above Ac3. After heating above the austenitizing temperature, the blank is placed in a hot forming press. The blank is deformed and simultaneously quenched (cooled rapidly). Cooling can generally be carried out at a rate above the so-called critical cooling rate.

[0006] The rapid development of electric vehicles (EVs) and hybrid vehicles has forced the industry to design new vehicle components, such as for weight reduction to achieve improved vehicle range, and for housing and protecting new vehicle components. Structural components with new geometries and alternative materials are being manufactured and integrated into EVs to achieve safety and weight reduction goals. Although reference will be made herein generally to electric vehicles or EVs, this is expressly intended to cover hybrid vehicles as well.

[0007] The traction battery is an integral part of the EV and is configured to provide electrical power to the vehicle's electric motor. The electronic and chemical properties of these batteries make them particularly sensitive to high mechanical loads (e.g., crash impact) and to high operating temperatures. In order to extend battery life, the automotive industry has invested considerable effort in providing battery housings and load-bearing structures suitable for EVs that incorporate battery protection and battery cooling. As a result, over the past few years, a wide variety of battery assemblies have been designed and developed to house and (mechanically and thermally) protect the traction battery.

[0008] Steel battery boxes or battery trays have been developed for this purpose. Polymer (plastic) or composite components are also known. Although plastics and composites can be lighter than metal components, they need to be designed and sized to protect against severe impacts. In addition, an appropriate cooling system must be provided to keep the battery temperature within an acceptable range while reducing the weight of the overall battery system.

[0009] An object of the present disclosure is to provide improvements in structures for protecting automotive batteries. Summary of the invention

[0010] In a first aspect, a battery unit for a vehicle is provided. The battery unit includes a battery tray made of a composite material. The battery tray defines an interior space configured to receive a battery including one or more battery cells. The battery tray is bounded by a bottom wall and one or more side walls. In addition, the battery unit includes a top cover configured to enclose the battery tray. In addition, a cooling system for cooling the battery is integrated in the top cover.

[0011] The composite battery tray can provide a lightweight structure for the battery cell. In addition, the composite material can be selected to provide customized mechanical strength, for example, the composite material can have higher strength in one direction than in another direction. In addition, the introduction of a top cover including a cooling system integrated therein provides effective cooling for the battery and at the same time reduces the overall weight of the battery cell by reducing excess material layers. Thus, the provided battery cell has the lightweight benefits of a cell made of a composite or polymer material, while at the same time it includes a cooling system integrated within the battery cell in a weight-saving configuration. In addition, the composite battery tray can integrate several functions into a single component, for example, a composite manufacturing process can facilitate the integration of different components in a single mold. In an example, the composite battery tray can completely replace a welded steel subassembly.

[0012] Throughout this disclosure, an “electric vehicle” or “hybrid vehicle” may be understood to include any vehicle having a traction battery that is at least partially configured to provide power to an electric drivetrain of the vehicle.

[0013] Furthermore, throughout this disclosure, references to "mechanical properties of a structure" may be understood to refer to the mechanical properties of the material from which the structure is formed. Thus, unless otherwise indicated, comparisons of mechanical properties of structures, components, or other parts refer to the material, not to the geometry or other characteristics of the material.

[0014] In an example, the composite material used to form the battery tray may include glass fibers, although other materials such as carbon fibers or aramid fibers may also be used.

[0015] In some examples, the battery tray can be made of sheet molding compound. Sheet molding compound is a composite material provided in sheet form. The sheet is typically made by extending a resin paste into a surface, on which chopped fibers are distributed. Another layer of resin is then added on top of the chopped fibers and compacted and stored while the sheet cures.

[0016] In an example, the battery tray can include a plurality of cross members configured to separate the battery cells. In addition, the cross members can increase the strength of the battery tray against, for example, bending loads. In addition, the cross members can be used to provide stability to the battery cells when the battery cells are installed in the battery tray. For example, cross members positioned in an offset manner along the battery tray to separate groups of battery cells (e.g., five cells or more) can facilitate the positioning of each group of battery cells.

[0017] In some examples, the battery tray includes a bracket configured to connect the battery tray to the vehicle frame. The bracket can be located at the side wall and manufactured integrally with the battery tray, or the bracket can be inserted later, for example, using fasteners, welding, or adhesives. In an example, the bracket can be located at two opposing side walls of the battery tray to provide stability for the connection to the vehicle frame.

[0018] In an example, the top cover is configured to at least partially seal the battery tray. For example, the top cover can be configured to limit the ingress of liquid into the battery tray and the egress of liquid from the battery tray. Thus, the top cover can protect the battery from the ingress of foreign particles and liquids that can damage the battery cells, and can also contain liquids that may be present in the battery. Thus, the top cover can serve as a cooling element and a sealing plate, thereby reducing the number of components and the associated weight of the battery cell.

[0019] In some examples, the top cover can include a seal substantially along a perimeter of the top cover. Additionally, the seal can be or include an adhesive adhered to at least one of the top cover and the battery tray. Additionally, the seal can include an adhesive greater than 1 W·m -1 ·K -1 , and more precisely above 1,5 W·m -1 ·K -1 In another example, the top cover can include a seal on substantially the entire inner surface of the top cover. For example, the seal can form a thin film between the top cover and the battery tray and between the battery cells in the battery tray.

[0020] In some examples, the cooling system includes one or more cooling channels configured to contain a liquid coolant. The cooling channel may have an input port and an output port to introduce the coolant at a relatively low temperature and extract the coolant at a relatively high temperature, respectively. The heated coolant may be cooled again by a heat exchanger before being reintroduced into the battery box for cooling.

[0021] The composition of the coolant can be selected to obtain a coolant with a high specific heat capacity (i.e., high heat capacity per unit of mass), or to obtain a coolant with a high latent heat (i.e., high heat absorption during phase change) and a phase change close to the operating temperature of the battery cell. Thus, a cooling system with cooling channels can keep the battery temperature of the battery below a critical temperature at which the battery may experience thermal runaway.

[0022] Thermal runaway can be understood as a chemical chain reaction that occurs within a battery cell after a critical temperature is reached. This type of chain reaction is usually complex to control once they start, so it is necessary to provide components and devices to control the battery temperature.

[0023] In an example, the top cover may be made of aluminum to provide a relatively light weight component with good heat transfer properties.A plurality of cooling channels through which a liquid coolant circulates may be formed, for example, in an extruded aluminum profile, or between two aluminum plates or sheets.

[0024] In an example, the aluminum profile, plate or sheet may be configured to be in contact with the battery cell, particularly through an interface material having high thermal conductivity, such as a sealant or filler material having high thermal conductivity.

[0025] In some examples, the battery includes a bus bar that electrically connects the battery cells. In addition, the bus bar can be configured to be at least partially located within the battery tray. In an example, the bus bar can be almost completely located within the battery tray. In an example, the bus bar can have a substantially U-shaped shape, the U-shaped shape including a first side member electrically connected to the positive terminal of the battery cell, a second side member electrically connected to the negative terminal of the battery cell, each of the side members connected to an electrical contact, which can be located near the center plane.

[0026] Additionally, in an example, the battery cell includes a layer above the top cover configured to provide flame retardant protection.

[0027] In another aspect, a battery system is provided comprising one or more battery cells as previously disclosed. Thus, for example in the event of a malfunction, individual battery cells of the battery system may be replaced, while other components of the battery system may remain unaffected / unchanged.

[0028] In an example, each battery cell of the battery system includes or can be connected to a separate battery management system (BMS). A BMS is an electronic system that manages the battery by protecting the battery from operating outside its safe operating range. For example, the BMS can monitor the voltage, temperature and current of the battery and battery cells, the cooling system and the balance state of the cells, etc. Having a separate BMS results in a battery system with battery cells that can operate completely independently of each other.

[0029] In some examples, the battery system includes a lower cover or lower cover component configured to cover the battery cells. Thus, a single lower cover (component) protects all battery cells from external impacts, dust, stones, bollards, etc. In addition, the lower cover can be designed to have a substantially flat bottom, which can reduce the drag coefficient of the vehicle. This can also improve the driving range of the electric vehicle.

[0030] In yet another aspect, a vehicle including the disclosed battery system is provided.

[0031] In the example, the battery cells are connected to the frame of the vehicle by releasable fasteners. Again, this allows the battery system to be disassembled without requiring any permanent modifications in the vehicle or in the battery cells. Since each cell can be essentially independent with its own cooling system, its own bus bars, etc., replacing one cell with a new one can be done relatively easily.

[0032] In some examples, the vehicle may include a battery system including two or more battery cells. In addition, the vehicle may include at least three coupling structures configured to receive releasable fasteners. The first and second coupling structures may be located at respective first and second sides of the battery system. In addition, the third coupling structure may be located between the battery cells and may be configured to receive releasable fasteners from two battery cells.

[0033] This vehicle configuration results in a compact design in which two battery cells can be independently mounted and connected to the vehicle. The battery cells can be positioned so as to lower the center of gravity of the vehicle and be distributed substantially symmetrically with respect to the central longitudinal axis of the vehicle. The coupling structure can provide a suitable connection area between the battery cells and the vehicle and can be integrated into or coupled to the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Non-limiting examples of the present disclosure will now be described with reference to the accompanying drawings, in which:

[0035] Figure 1 An exploded view of an example of a battery cell according to the present disclosure is schematically shown.

[0036] Figure 2 An exploded view of an example of a battery system according to the present disclosure is schematically shown.

[0037] Figure 3 The vehicle according to the present disclosure is schematically shown. Figure 2 A perspective bottom view of the battery system in FIG.

[0038] Figure 4 Schematically shows the Figure 3 A cross section of the plane A-A'.

[0039] Figure 5 Schematically shows the Figure 3 Cross section of plane BB'.

[0040] The drawings relate to example implementations and are intended only to aid in understanding the claimed subject matter and are not intended to limit the same in any sense. DETAILED DESCRIPTION

[0041] Figure 1 A battery unit 100 for a vehicle is schematically shown. The battery unit 100 includes a battery tray 10 made of a composite material. The battery tray 10 defines an inner space configured to receive a battery 20 including one or more battery cells. The battery tray 10 is bounded by a bottom wall 11 and at least one side wall 12. In addition, the battery unit 100 includes a top cover 50 configured to enclose the battery tray 10. A cooling system 53 for cooling the battery 20 is integrated in the top cover 50.

[0042] The battery tray 10 is made of a composite material (e.g., a fiber-reinforced polymer), and the composite material can be selected and customized to provide specific mechanical properties to the battery tray 10. For example, the composite material can include biaxial or triaxial fiber layers to increase the mechanical properties of the tray in a specific direction. In addition, the materials of the fibers and resins can also be selected to obtain a final product, i.e., the battery tray 10, having specific mechanical and physical properties. For example, the fibers can include glass fibers, carbon fibers, or aramid fibers, etc. By selecting appropriate polymers and fibers, the battery can be electrically insulated from the rest of the vehicle.

[0043] In some examples, the composite battery tray 10 can be manufactured using compression molding or sheet molding compound. In this case, the sheet molding compound (SMC) can be cut into pieces of appropriate size and placed in a heated mold of a mold. In an example, the heated mold can be at a temperature between 130°C and 160°C. The molds of the mold can then be put together and closed, applying a pressure of 30 to 120 bar. Thus, when the viscosity of the material decreases, the SMC flows and fills the mold cavity. Note that other techniques in which the pressure applied to the SMC is quite low, i.e., less than 30 bar, can also be used.

[0044] SMC made from fiberglass can cure between 30 seconds and 150 seconds after starting the forming process. Therefore, the entire manufacturing cycle can be as fast as 80 seconds, allowing high-volume production at reduced material costs.

[0045] The composition of the SMC can be adapted to provide a composite material with improved properties. For example, carbon fibers can be introduced into the SMC to increase the strength- and stiffness-to-weight ratio. In addition, other additives can be provided to prevent surface microcracks caused by degassing.

[0046] In other examples, the composite battery tray 10 can be manufactured by hand layup, which includes manually placing layers of, for example, dry fabric onto a tool (mold) to form a laminate stack. Resin can then be applied to the dry fabric, for example, by resin infusion or injection using RTM. In other examples, prepregs (fabrics pre-impregnated with resin) can be used. After the prepregs are laid, they can be heated and cured.

[0047] In other cases, the manufacturing process may include laying down fabric that has been coated with resin and then compacting the stack. Compaction may be done by hand, by rollers, or using vacuum bagging techniques.

[0048] It should be noted that Figure 1 The battery tray 10 in the example also includes cross members 13 between the side walls 12, which are configured to separate battery cells or groups of battery cells. Therefore, the cross members act as "spacers" or "dividers". When multiple battery cells that make up the battery 20 are installed inside the tray, the spacers can help separate the cells from each other and help stabilize them during assembly. In addition, the cross members 13 can be designed to provide rigidity to the tray 10.

[0049] In some examples, the battery cells may be secured to the bottom wall 11 of the battery tray 10 using a (structural) adhesive, with the cross members providing additional stability to the assembly. Structural adhesives may be considered herein as high strength glues that can bond components together in a load-bearing structure.

[0050] In this example, the cross member 13 can be integrally formed with the battery tray 10. For example, the mold used to manufacture the battery tray 10 can include such a geometry, and the cross member 13 can be formed of a composite material. In other examples, the cross member 13 can be made of a different material, such as other composite materials, or, for example, a suitable polymer material.

[0051] These cross members can extend from the bottom wall 11 to the uppermost portion of the battery tray 10, or gaps can be left. Such gaps can enhance airflow circulation and battery cooling. In addition, the number and spacing between the cross members 13 can be adapted according to several battery parameters, such as the number of battery cells, the width of the battery cells, the structural requirements of the battery tray, and other parameters.

[0052] Likewise Figure 1 As shown, the battery tray 10 can include brackets 14 configured to connect the battery tray 10 to the vehicle frame. The brackets can also be formed integrally with the battery tray 10, or can be coupled to the battery tray 10 after being formed. In this example, the battery tray 10 includes fourteen brackets 14, with seven brackets on two opposing sides of the battery tray 10, but other numbers of brackets 14 and arrangements around the battery tray 10 can also be used.

[0053] also, Figure 1It is shown that the battery cells of the battery 20 can be electrically connected using a bus bar 30. In this example, the bus bar 30 has a generally U-shaped shape. Thus, a first side member 31 of the bus bar 30 is electrically connected to the positive terminal of the battery cell, and a second side member 32 is electrically connected to the negative terminal of the battery cell. Each of the side members 31, 32 can be connected to an electrical contact of the battery cell, i.e., a main electrical connector. The main electrical connector can be located substantially in a central longitudinal position of the cell.

[0054] also, Figure 1 The battery cell 100 in FIG. 1 shows that the top cover 50 is configured to at least partially seal the battery tray 100. In this example, the top cover 50 includes a seal 40 substantially along the perimeter or peripheral edge of the top cover 50. This promotes a nearly uniform seal along the entire perimeter of the battery tray 10 and reduces the risk of liquid ingress or egress.

[0055] In some examples, the seal 40 may include an adhesive, for example, the seal may be adhered to the top cover 50 and then press-fit into a recess in the battery tray 10. In other examples, the seal may be adhered to both the top cover 50 and the battery tray 10. Furthermore, in some cases, the connection between the top cover 50 and the battery tray 10 may be achieved by a combination of geometric interference effects, such as press-fitting the seal 40 into the recess, and an adhesive. Additionally, other fastening elements such as releasable fasteners may be used to mechanically secure the connection between the top cover 50 and the battery tray 10.

[0056] In an example, the seal 40 can be positioned, for example adhered to a majority of the inner surface of the top cover 50. In addition, the seal 40 can also be adhered to the battery tray 10. A thermally conductive adhesive can be used to connect the battery cells to the top cover to improve thermal control of the battery cells. Therefore, the adhesive in this example can provide sealing, structural bonding, and thermal conductivity.

[0057] In further examples, the battery tray 10 and the top cover 50 may define a substantially labyrinthine interface to even further impede the ingress / egress of liquids.

[0058] In addition, the top cover 50 can be made of a metal having a relatively high thermal conductivity and a relatively low density, such as aluminum. However, other materials or combinations of materials can also be used for this purpose, such as aluminum alloys.

[0059] In addition, the top cover 50 may include a cooling system 53 having one or more cooling channels configured to contain a liquid coolant. The cooling system may be formed by controlled atmosphere brazing (CAB). In addition, the cooling system may be manufactured after any other suitable manufacturing process, such as machining a blank, welding a bent portion to a flat plate, metal molding, deforming a plate such as an aluminum plate to define an open cooling channel, and coupling another plate (deformed or flat) to close the cooling channel, etc.

[0060] Any suitable coolant may be used, such as water or a more elaborate composition, such as one comprising ethylene glycol. In one specific example, a composition comprising 50% glycol and 50% water may be used.

[0061] As previously mentioned, the composition of the coolant can be selected to obtain a coolant with a high specific heat capacity (i.e., high heat capacity per mass unit), or to obtain a coolant with a high latent heat (i.e., high heat absorption during phase change) and a phase change close to the operating temperature of the battery cell. In addition, the coolant can have low conductivity or electrically insulating properties. In an example, the coolant can be a dielectric coolant. Thus, a cooling system with cooling channels can maintain the battery temperature at a suitable operating temperature, i.e., a temperature at which the battery does not experience problems and it operates effectively. In any case, the cooling system can ensure that the temperature is maintained below a critical temperature at which the battery may experience thermal runaway.

[0062] In an example, the cooling system can also be used to heat the monomers to a suitable operating temperature. For example, the cooling system can heat the monomers during an initial heating process and then cool the monomers after the monomers reach the desired operating temperature.

[0063] In addition, the cooling channel may have an inlet port 51 and an outlet port 52 to introduce coolant at a relatively low temperature and extract coolant at a relatively high temperature, respectively. The inlet port 51 and the outlet port 52 may be connected to a heat exchanger and a pressurization system. Figure 1 Each battery cell 100 shown can have its own cooling system and its own thermal management system, i.e., the thermal management of a cell 100 can be independent of the thermal management of adjacent cells in the same vehicle. If a cell is damaged or requires repair, it can simply be replaced without affecting the functionality of other cells in the same vehicle.

[0064] also, Figure 1 The example of the battery cell 100 shown in FIG. 1 shows that the battery cell 100 may also include a layer 60 above the top cover 50 to provide fire protection and at least partially isolate the battery cell 100 from other components of the vehicle. The layer 60 may be shaped to at least partially match the geometry of the top cover 50 in which the cooling channels 53 are integrated. In practice, in Figure 1 In the example shown, the layer 60 can be formed by spraying a composition comprising an epoxy resin. The composition can thus be adapted to the geometry of the top cover before curing, thereby producing a layer with a substantially constant material thickness.

[0065] The layer providing flame retardancy can generally be made of a coating material. The coating material can be a composition comprising an epoxy resin and can be cured at room temperature or a higher temperature to accelerate the curing process. In an example, other materials such as fiber cloth or mica board can be used to provide flame retardant protection.

[0066] Figure 2 is a schematic diagram of a battery system 1000 including two battery cells 100. In other examples, the battery system may include any other number of battery cells, such as three or more battery cells.

[0067] In the example shown, the battery system 1000 includes two substantially similar battery cells 100 , but in other examples, the battery system 1000 may include battery cells 100 of different specifications, including the number of cells, battery capacity, battery size, etc.

[0068] In the illustrated example of the battery system 1000, each battery cell 100 includes a separate battery management system 400. Note that the battery management system has been schematically illustrated, and the connections between the battery and the battery management system are not illustrated. As previously discussed, the battery management system can be configured to monitor the voltage, temperature, and current of the battery and battery cells, the cooling system and the equilibrium state of the cells, etc. In addition, the battery management system can be configured to send control signals to other electronic components of the battery cell to modify any of the aforementioned parameters or other parameters.

[0069] Thus, the battery system 1000 may include more than one battery cell 100 which may be considered as independent units, ie a battery cell may operate the vehicle without affecting other battery cells, in particular in terms of electrical operation (power, voltage, current, etc. and in terms of cooling).

[0070] In addition, the battery system 1000 may include a lower cover 200 configured to cover the battery cells 100. The lower cover 200 may protect the battery cells 100 from impact from below the vehicle. The lower cover 200 may be a metal component, such as a hot stamped metal component.

[0071] In some examples, the lower cover 200 can be made of boron steel, such as 22MnB5 steel (e.g., commercially available from Arcelor Mittal) with or without a protective coating. 1500), or 37MnB5 steel (e.g. 2000) or any martensitic steel or ultra high strength steel (UHSS). 1500 and similar 22MnB5 steels are usually supplied in a ferrite-pearlite phase. It is a fine grain structure distributed in a uniform pattern. Its mechanical properties are related to this structure. After heating, the hot stamping process and subsequent quenching, a martensitic microstructure is produced. As a result, tensile strength and yield strength increase significantly.

[0072] The composition of 1500 is summarized in weight percentage as follows (the balance is iron (Fe) and impurities):

[0073] Maximum carbon (C) (%): 0.25

[0074] Maximum Silicon (Si) (%): 0.4

[0075] Maximum manganese (Mn) (%): 1.4

[0076] Maximum phosphorus (P) (%): 0.03

[0077] Maximum sulfur (S) (%): 0.01

[0078] Aluminum (Al) (%): 0.01-0.1

[0079] Maximum titanium (Ti) (%): 0.05

[0080] Maximum niobium (Nb) (%): 0.01

[0081] Maximum copper (Cu) (%): 0.20

[0082] Maximum boron (B) (%): 0.005

[0083] Maximum chromium (Cr) (%): 0.35

[0084] 2000 is another boron steel with higher strength. After the hot stamping die quenching process, The yield strength of 2000 may be 1300 MPa or higher, and its ultimate tensile strength may be higher than 1800 MPa.

[0085] The composition of 2000 is summarized in weight percentage as follows (the balance is iron (Fe) and impurities):

[0086] Maximum carbon (C) (%): 0.36

[0087] Maximum Silicon (Si) (%): 0.8

[0088] Maximum manganese (Mn) (%): 0.8

[0089] Maximum phosphorus (P) (%): 0.03

[0090] Maximum sulfur (S) (%): 0.01

[0091] Aluminum (Al) (%): 0.01-0.06

[0092] Maximum titanium (Ti) (%): 0.07

[0093] Maximum niobium (Nb) (%): 0.07

[0094] Maximum copper (Cu) (%): 0.20

[0095] Maximum boron (B) (%): 0.005

[0096] Maximum chromium (Cr) (%): 0.50

[0097] Maximum Molybdenum (Mb) (%): 0.50

[0098] 22MnB5 may have an aluminum-silicon coating to avoid decarburization and scaling during the forming process. Several 22MnB5 steels are commercially available, with similar chemical compositions. However, the exact amounts of each component in the 22MnB5 steel may vary slightly from one manufacturer to another. Other ultra-high strength steels include, for example, BTR 165 commercially available from Benteler.

[0099] In addition, the lower cover 200 may be made of other high-strength steel. For example, Steel can also be used to manufacture the lower cover 200 by a cold forming process. Compared with parts made of DP steel with similar mechanical properties, The lower cover 200 can provide additional weight reduction. Steel exhibits excellent fatigue properties due to its very high mechanical strength. Steel is commercially available from ArcelorMittal.

[0100] In some examples, the lower cover 200 may be made of For example, the lower cover 200 may be made of 1180 (HF1180Y850), which has a tensile strength of 1180 to 1330 MPa. In other examples, the lower cover 200 may be made of Made of S1270, it has a tensile strength of 1270 to 1400 MPa.

[0101] The composition of 1180 is summarized as follows in weight percentage (the balance is iron (Fe) and impurities):

[0102] Maximum carbon (C) (%): 0.23

[0103] Maximum Silicon (Si) (%): 2.0

[0104] Maximum manganese (Mn) (%): 2.9

[0105] Maximum phosphorus (P) (%): 0.040

[0106] Maximum sulfur (S) (%): 0.010

[0107] Aluminum (Al) (%): 0.015-1.0

[0108] Maximum titanium and niobium (Ti+Nb) (%): 0.15

[0109] Maximum niobium (Nb) (%): 0.10

[0110] Maximum copper (Cu) (%): 0.20

[0111] Maximum boron (B) (%): 0.005

[0112] Maximum chromium and molybdenum (Cr+Mo) (%): 0.60

[0113] The composition of S1270 is summarized as follows in weight percentage (the balance is iron (Fe) and impurities):

[0114] Maximum carbon (C) (%): 0.21

[0115] Maximum Silicon (Si) (%): 1.5

[0116] Maximum manganese (Mn) (%): 4.1

[0117] Maximum phosphorus (P) (%): 0.04

[0118] Maximum sulfur (S) (%): 0.01

[0119] Aluminum (Al) (%): 0.015-1.0

[0120] Maximum titanium and niobium (Ti+Nb) (%): 0.15

[0121] Maximum niobium (Nb) (%): 0.10

[0122] Maximum copper (Cu) (%): 0.2

[0123] Maximum chromium and molybdenum (Cr+Mo) (%): 0.6

[0124] Steels having other material compositions suitable for hot forming and cold forming may also be used to manufacture the lower cover 200 .

[0125] In addition, the lower cover 200 may have an electrical adapter to connect the battery unit 100 to other components of the vehicle. The electrical adapter may have multiple ports. In some examples, the ports may be configured to provide different electrical outputs, i.e., the maximum voltage and / or current provided by each port may be different.

[0126] In some examples, the lower cover 200 may include a vent, such as an additional port (not shown), to allow battery gases to escape to the atmosphere. Additional vents configured for the same purpose may also be used in the battery tray 10 .

[0127] also, Figure 2 Also shown are coupling structures 300, 310 of the vehicle. The coupling structures 300, 310 are configured to receive releasable fasteners so that the battery system can be coupled to the vehicle. These structures will be combined with Figures 3 to 5 for a more detailed discussion.

[0128] Figure 3 Schematically illustrated is a perspective bottom view of an example of a vehicle frame 1500 of a vehicle according to the present disclosure. Note that for simplicity, other vehicle components that are not mechanically coupled to the battery system 1000 are not shown.

[0129] The vehicle in this example includes a battery system 1000 including two battery cells covered by a lower cover 200. In this example, the lower cover 200 also includes other openings configured to receive an electrical adapter 210 and an inlet port 51 and an outlet port 52 of a cooling system.

[0130] Likewise Figure 3 As shown, the lower cover 200 can have a substantially flat bottom. Therefore, the underbody of the vehicle can remain substantially flat, thereby enhancing the aerodynamic performance of the vehicle. In other examples, the lower cover 200 can be adapted to be progressively adjusted to the underbody diffuser of the vehicle.

[0131] Figure 4 Schematically shows the Figure 3 In this figure, only half of the vehicle frame 1500 and the battery system 1000 are shown.

[0132] Figure 4It is shown that the battery tray 10 can be connected to the coupling structure 300, 310 by a releasable fastener 141. In this example, the bracket 14 of the battery tray 10 is an element of the battery tray 10, which is configured to receive the fastener 141 and hold the battery tray 10 in place. In addition, the lower cover 200 may also include a flange configured to receive the releasable fastener 241 and connect the lower cover 200 to the vehicle frame 1500. Therefore, in the event that a qualified operator needs to enter the interior of the battery system 1000, the operator can release the fastener 241 of the lower cover 200, remove the lower cover 200 and remove the specific battery cell 100 from the rest of the vehicle. If necessary, the battery cell 100 can be replaced by another battery cell. The operation of the adjacent battery cells is essentially independent of the new battery cell (in terms of electrical control and in terms of cooling) and is therefore essentially unaffected.

[0133] also, Figure 4 It is shown that the bottom wall 11 of the battery tray 10 can be separated from the lower cover 200. Therefore, any impact received by the lower cover 200 is not directly transmitted to the battery tray 10. In other examples, an intermediate buffer layer including, for example, foam or honeycomb material can be located between the lower cover 200 and the bottom wall 11 of the battery tray 10.

[0134] Figure 4 The arrangement of the coupling structures 300, 310 is partially shown. More specifically, Figure 4 The vehicle is shown to include at least three coupling structures 300 , 310 (one not shown). The first and second coupling structures 300 may be located at respective first and second sides of the battery system 1000 , and the third coupling structure 310 may be located between the battery cells 100 of the battery system 1000 .

[0135] Thus, each of the first and second connecting structures 300 can be configured to secure the corresponding battery cell 100 to a side structure (which can be, for example, a rocker, depending on the vehicle frame), and the third connecting structure 310 can be configured to secure two battery cells 100 to each other and to the frame of the vehicle.

[0136] The coupling structures may be configured for receiving releasable fasteners, and thus the battery system may be assembled and disassembled to the vehicle multiple times without incurring any structural modifications to the vehicle.

[0137] In an example, the coupling structures may be made from extrusions, such as aluminum extrusions.

[0138] Figure 5 Schematically shows the Figure 3 Cross section of plane BB'.

[0139] The vehicle's coupling structure 310 can extend substantially along the entire length of the battery tray 10 to facilitate connection between the battery tray 10 and the vehicle. In other examples, the coupling structure 310 can be much shorter than the battery tray 10, and multiple coupling structures 310 can be distributed along the length of the battery tray 10.

[0140] In an example, the coupling structures 300, 310 can be coupled to the vehicle frame 1500 by welding (e.g., spot welding), but other methods may also be used. For example, the coupling structures 300, 310 may be integrally formed in the vehicle frame. In addition, the coupling structures 300, 310 may be made of a metal with high mechanical properties. For example, the coupling structures 300, 310 may be made of a suitable steel (e.g., 22MnB5 or 37MnB5 or other boron steels), as previously discussed with respect to the lower cover 200.

[0141] Figure 5 It is also shown that the lower cover 200 may be adapted to receive other components of the battery system 1000 , for example, it may include ports 51 , 52 for a cooling system 53 and an opening for an electrical adapter 210 .

[0142] Although only a plurality of examples are disclosed herein, other replacements, modifications, uses and / or their equivalents are possible. In addition, all possible combinations of the described examples are also contemplated. Therefore, the scope of the present disclosure should not be limited by the specific examples, but should only be determined by a reasonable reading of the appended claims.

Claims

1. A battery unit for a vehicle, the battery unit comprising: A battery tray made of a composite material and defining an interior space configured to receive a battery including one or more battery cells, the interior space being bounded by a bottom wall and one or more side walls, and the battery tray comprising a plurality of cross members configured to separate the battery cells and formed integrally with the battery tray, and a top cover configured to close the battery tray, wherein A cooling system for cooling the battery is integrated into the top cover, and wherein The top cover includes a seal at least substantially along a perimeter of the top cover, wherein the seal is a thermally conductive seal and is arranged to contact the top cover and the battery cell. 2 . The battery cell according to claim 1 , wherein the battery tray is made of sheet molding compound.

3. The battery cell according to any one of claims 1 and 2, wherein the composite material comprises glass fibers.

4. The battery unit according to any one of claims 1 to 3, wherein the battery tray includes a bracket configured to connect the battery tray to a vehicle frame.

5. The battery cell according to any one of claims 1 to 4, wherein the top cover is made of aluminum.

6. The battery cell of any one of claims 1 to 5, wherein the seal comprises an adhesive.

7. The battery unit according to any one of claims 1 to 6, wherein the battery includes a bus bar electrically connecting the battery cells, the bus bar being at least partially located within the battery tray. 8 . The battery unit of claim 7 , wherein the bus bar has a substantially U-shape including a first side member electrically connected to a positive terminal of the battery cell and a second side member electrically connected to a negative terminal of the battery cell.

9. A battery system comprising one or more battery cells according to any one of claims 1 to 8.

10. The battery system of claim 9, wherein each battery cell includes an individual battery management system. 11 . The battery system according to claim 9 or 10 , wherein the battery system comprises a lower cover configured to cover the battery cell.

12. A vehicle comprising a battery system according to any one of claims 9 to 11.

13. The vehicle of claim 12, wherein the battery unit is connected to a frame of the vehicle by releasable fasteners.

14. The vehicle of claim 13, wherein the battery system comprises two battery cells, and wherein the vehicle further comprises at least three connecting structures configured to receive the releasable fasteners, wherein the first and second connecting structures are located at a first side and a second side of the battery system, respectively, and the third connecting structure is located between the two battery cells and is configured to receive the releasable fasteners from the two battery cells.

Images