ELECTRIC VEHICLE BATTERY ENCLOSURE

A battery enclosure includes a tub defining an internal volume, a lid, a cross member within the internal volume, and a mounting bracket. The tub has a bottom and a wall integrally formed with the bottom. The lid is configured to couple to the wall to enclose the internal volume. The cross member is coupled to the tub. The mounting bracket is attached to the bottom of the tub and is configured to releasbly secure a battery.

BACKGROUND

The present disclosure relates generally to the field of battery enclosures for vehicles. More specifically, the present disclosure relates to battery enclosures for use in electric vehicles (EVs). Typical battery enclosures include a multi-piece construction that requires the application of a water tight seal between a bottom plate and a plurality of side walls. Existing battery enclosures require processes and materials that add labor and complexity to the fabrication and assembly processes. Typical battery enclosures require strict tolerances between components for assembly and the application of sealing methods following assembly. Additionally, the sealed interfaces between the side walls and bottom are subject to failure modes including leaking and fracture. Existing tub designs are typically heavy and require an undesirable amount of material, time, and cost to manufacture.

SUMMARY

At least one embodiment relates to a battery enclosure for enclosing batteries for an electric vehicle. The battery enclosure includes a tub defining an internal volume, a lid, a cross member within the internal volume, and a mounting bracket. The tub has a bottom and a wall integrally formed with the bottom. The lid is configured to couple to the wall to enclose the internal volume. The cross member is coupled to the tub. The mounting bracket is attached to the bottom of the tub and is configured to releasably secure a battery.

In some embodiments, the cross member is formed at least partially using a roll forming process.

In some embodiments, the cross member extends laterally across the internal volume.

In some embodiments, the cross member is formed from a single piece of material.

In some embodiments, the lid is supported by the wall and at least one battery coupled to the mounting bracket.

In some embodiments, the wall defines an interior surface. In some embodiments, the cross member includes a first end and a second end. In some embodiments, the first end is coupled to a first portion of the interior surface and the second end is coupled to the second portion of the interior surface.

In some embodiments, the cross member is coupled to the bottom between the first end and the second end.

In some embodiments, the cross member is a first cross member. In some embodiments, the battery enclosure includes a second cross member coupled to the tub and spaced from the first cross member.

In some embodiments, the mounting bracket is coupled to the bottom between the first cross member and the second cross member.

In some embodiments, the bottom includes stiffening features formed in a space between the first cross member and the second cross member.

Another embodiment relates to a battery enclosure for an electric vehicle. The battery enclosure includes a metal tub, a lid, multiple supports and a mounting plate. The metal tub defines an internal volume. The lid is configured to couple to the metal tub to enclose the internal volume. The multiple supports are within the internal volume and are coupled to the metal tub. The multiple supports include a first support and a second support. The mounting plate is coupled to the metal tub within a space between the first support and the second support. The multiple supports are configured to surround a battery within the internal volume on two sides of the battery.

In some embodiments, the metal tub is formed from a single sheet of metal and is formed from a single sheet of metal via a deep-drawing process.

In some embodiments, the single sheet of metal is steel or aluminum, and the thickness of the metal is between 0.5 mm and 2 mm.

In some embodiments, the plurality of supports include martensitic steel.

In some embodiments, the plurality of supports are shaped via a roll forming process.

Another embodiment relates to a method. The method includes forming, via a stamping process, a tub having a bottom and a continuous side wall integrally formed with the bottom. The tub defines an internal volume. The method further includes attaching a plurality of cross members to the tub within the internal volume. The plurality of cross members are fabricated via a roll forming process. The method further includes coupling a mounting bracket to the bottom of the tub. The mounting bracket configured to secure at least one battery. The mounting bracket is configured to secure at least one battery. The method further includes coupling at least one battery to the mounting bracket within the internal volume and coupling a lid to the tub to thereby enclose and seal the internal volume.

In some embodiments, the method includes, subsequent to forming the tub, forming stiffening features in the bottom of the tub.

In some embodiments, the tub is made of a single piece of steel or aluminum having a thickness between 0.5 mm and 2.0 mm.

In some embodiments, the plurality of cross members are coupled to at least three internal faces of the tub.

In some embodiments, an average material thickness of the continuous side wall is less than an average material thickness of the bottom.

This summary is illustrative only and should not be regarded as limiting.

DETAILED DESCRIPTION

Referring generally to the FIGURES, disclosed herein is a battery enclosure (e.g., battery container, battery housing, battery compartment, etc.) for vehicles that utilize electric energy (e.g., hybrid vehicles, electric vehicles, autonomous electric vehicles, unmanned electric vehicles, etc.) to create useful work (e.g., forward propulsion of the vehicle, non-propulsion applications, etc.). The battery enclosure may be for any vehicle type (e.g., sedan, truck, van, transit vehicle, commercial vehicle, semi-truck, hauling equipment, work vehicles, etc.) and may be positioned on the vehicle in various arrangements. According to some embodiments, the battery enclosure may be used on-board any vehicle that is partially or fully propelled by electric energy (e.g., electricity) and is configured to house energy storage devices (e.g., batteries, capacitors, etc.) for electric energy storage on-board the vehicle. In an exemplary embodiment, the battery enclosure is mounted to the chassis below the vehicle's cabin and is used to secure enclosed batteries to the vehicle.

Still referring generally to the FIGURES, the battery enclosure is advantageously sealed to prevent any inadvertently leaked electrolyte (or other contaminate or chemical) from reaching the external environment. The side walls of the battery enclosure are integrally formed with the bottom of the enclosure through a stamping process to reduce the complexity, weight, cost, and likelihood of failure (e.g., leaking) of the battery enclosure. Additionally, the integrally formed walls of the single-piece tub design reduce the amount of time and material required to fabricate the battery enclosure. In some embodiments, the battery enclosure is configured to protect the enclosed batteries from debris or obstructions in the surrounding environment (e.g., dirt, rocks, liquids, curbs, poles, etc.).

Referring toFIG. 1, a battery enclosure (e.g., battery container, battery housing, battery compartment, etc.) is shown as battery tub assembly100according to one embodiment. The battery tub assembly100includes a tub (e.g., container, tray, etc.), shown as tub101, cross members or supports (e.g., stringers, cross bars, etc.) shown as stringers206, and mounts (e.g., mounting brackets, fixing bracket, fastening bracket, etc.), shown as mounting brackets204. The tub101includes a bottom (e.g., base, floor, etc.) shown as bottom102, and a wall, shown as wall104. The wall104and bottom102define an internal volume106. In some embodiments, the wall104is integrally formed with the bottom102and is continuous about the periphery of the bottom102. In some embodiments, the wall104has an upper edge, shown as upper edge112, an interior surface105, and an outer surface. As shown inFIGS. 1-5, the upper edge112includes a flange108. As shown inFIG. 4, the flange108is configured to be sealed to a lid216. As shown inFIG. 1, the stringers206are attached (e.g., welded, bonded, adhered, bolted, etc.) to the wall104and the bottom102. In some embodiments, the stringers206may be attached to the bottom102along their length to improve the structural integrity of the tub101. For example, some or all of the length of the stringers206may be attached to the bottom102.

As shown inFIG. 2, according to one embodiment, tub101is formed from a single-piece of material. In an exemplary embodiment, the single-piece of material is formed (e.g., stamped, deep-drawn) into a tub shape which defines bottom102and wall104. In some embodiments, the tub shape may have substantially different proportions than the proportions of tub101shown inFIG. 2. For example, the wall104of the tub101may be taller or shorter than shown inFIG. 2, and the flange108may be smaller or larger. In some embodiments, the flange108may include features to facilitate mounting to the lid216and/or to the vehicle. Additionally, in some embodiments, the bottom102may be in a shape such as a substantially rectangular, circular, elliptical, triangular, or polygonal shape, or any combination thereof. In an some embodiments, the bottom102is substantially flat. However, in other embodiments, the bottom102is not flat or substantially flat, and may be fabricated in other shapes and forms to accommodate various batteries, combinations of batteries, and/or various design constraints of one or more electric vehicles for which the battery enclosure is intended to be implemented.

The tub101may be made of a metal (steel, aluminum, etc.), a metal alloy, polymer, composite material, or any combination thereof. In an exemplary embodiment, the tub101has a material thickness that is suitable for a stamping process (e.g., deep-draw stamping, deep-drawing, metal stamping, etc.). In an exemplary embodiment, the tub101is stamped from a single sheet of steel (e.g., DP600) at a thickness of 1 mm. In other embodiments, the tub101is formed (e.g., stamped) from other grades, thicknesses, and/or types of materials. For example, the tub may be made from aluminum (e.g., Aluminum 6061) and may have a material thickness (e.g., an average material thickness) of 2 mm. In some embodiments, the thickness of the tub material ranges from 0.5 mm to 2.0 mm. For example, the material thickness of the wall104may be approximately 0.5 mm and the material thickness of the bottom may be approximately 2.0 mm. In some embodiments, at least a portion of the wall has a material thickness that is less than the material thickness than the bottom (e.g., the average material thickness of the bottom). The thickness of the tub101material may be selected based on material specific properties and characteristics (e.g., formability, drawability, Lankford coefficient, fracture strain, strength, hardness, etc.). In some embodiments, the thickness of the material selected for the tub101is substantially uniform prior to stamping. For example, the material selected for the tub101may be a sheet or blank (e.g., a metal sheet, sheet metal, a blank, etc.). In some embodiments, the material thickness of the wall104is thinner than the bottom102due to elongation of the material in the wall104that occurs during the stamping process (e.g., deep-drawing, deep-drawn stamping, metal pressing, etc.). In some embodiments, the material for the tub101is pressed into a die or several successive dies to achieve the final shape the tub101.

As shown inFIG. 2, the material of tub101plastically deforms and work hardens during the forming process (e.g., stamping process, deep-drawing process, etc.) and causes the hardness of the material to increase. In an exemplary embodiment, the enhanced hardness and strength of the tub101contributes to the structural integrity and rigidity of the battery tub assembly100. In some embodiments, the tub101may be heat treated to increase the hardness of the material using a heat treatment process. For example, the tub101may be hardened by heating the tub101material above the normalizing (e.g., critical) temperature and then quickly cooling the material (e.g., quenching). In some embodiments, the tub101may be tempered. In an exemplary embodiment, stiffening features (e.g., beading, corrugation, ribbing, etc.), shown as stiffening features110(seeFIG. 1), may be added to the tub101to work harden areas of the tub101(e.g., areas near the mounting brackets204) to enhance the structural rigidity of the tub101. In some embodiments, the tub101undergoes a stress relieving process (e.g., annealing) to restore material elasticity and ductility which improves the workability and drawability of the material for subsequent shaping or forming processes (e.g., stamping, drawing, punching, rolling, etc.).

Referring toFIG. 3, the battery tub assembly100is shown in an exploded view with a number of batteries (e.g., a battery array), shown as batteries202, in an offset position above the battery tub assembly100according to one embodiment. The battery tub assembly100includes mounting brackets204. In some embodiments, the mounting brackets204are fixedly coupled (e.g., welded, mounted, fastened, adhered, etc.) to an internal surface of the tub101. In an exemplary embodiment, the mounting brackets204are fixedly coupled to the interior surface of the bottom102. In an embodiment, the mounting brackets204may be configured to releasably secure the batteries202in a fixed position. For example, the mounting brackets204may include threaded holes that are configured to receive a fastener (e.g., a securing bolt) that secures a flange on a battery202to the mounting bracket204. As shown inFIG. 3, the stringers206extend laterally across the internal volume106. As shown inFIG. 5, the stringer206has a first end210and a second end212. In an exemplary embodiment, the first end210and the second end212are fixedly coupled to internal faces (e.g., faces of the interior surface105) of wall104. In some embodiments, the stringer206is coupled to at least one internal face of the tub101. For example, the stringer206may be attached to one or more internal surfaces and/or internal faces of the tub101. In some embodiments, the stringers206are interspaced by a width suitable for fitting a battery. For example, the stringers206may be spaced by a width, height, length, diameter, or other measures of battery202. As shown, the spaces between the stringers206may be sized and shaped to accommodate one or more battery202and may have one or more mounting bracket204. In some embodiments, the batteries202are positioned within the internal volume such that a stringer206surrounds each of the batteries202on at least two sides of the battery. In this way, the stringers206may advantageously support and protect the batteries202when the batteries202are installed within the internal volume106.

Referring toFIG. 4, the battery tub assembly100is shown with the batteries202releasably secured to the mounting brackets204by a securing mechanism (e.g., at least one of a nut/bolt configuration, fastener, snap-fit fastener, etc.). In some embodiments, the shape of the flange108is formed by a material removal process (e.g., a trimming process) that removes excess material utilized during a process that forms the wall104and bottom102(e.g., a drawing process). As shown inFIG. 4, the lid216has an outer edge (e.g., edge, periphery, outermost edge, rim, etc.), shown as rim218. In some embodiments, the lid216may be substantially flat, or may be a concave and/or convex shape. In some embodiments, the lid216may include stiffening features (e.g., stiffening features110) and may be formed by a stamping process. In some embodiments, the rim218may be shaped to align with the upper edge112of the tub101(e.g., shaped similarly to flange108). The lid may be supported by the wall104at the rim218, and may also be supported by other features mounted to the interior of the tub101. For example, the lid216may be supported by both the wall104and an interior feature (e.g., a rubber pad) situated on a battery202. In some embodiments, the lid216is made of a material similar to or the same as the material of the tub (e.g., steel, aluminum, etc.). In some embodiments, the lid216is configured to be fixedly coupled (e.g., welded, adhered, bonded, fastened, etc.) and sealed (e.g., using a sealant such as polyurethane) to the flange108to completely enclose and seal the internal volume106. Advantageously, the one-piece design of the tub101does not require additional sealing between the wall104and bottom102, according to some embodiments. In an exemplary embodiment, the tub101is sealed between the rim218and the flange108to completely seal and enclose the internal volume106.

Referring toFIG. 5, the stringer206is shown in greater detail according to one embodiment. The stringer206includes a first end210, a second end212, and a length extending from the first end210to second end212, shown as length214. In an exemplary embodiment, the stringers206have a height that is greater than their width to resist bending about the neutral axis in the plane containing the height. The disproportionate height and width of the stringer206may be facilitate an material efficient design, which may reduce the overall weight of the stringer206, and thereby reduce the weight of the battery tub assembly100. Ultimately, a reduction in weight of the battery tub assembly100may facilitate an improved range and efficiency of an associated electric vehicle. In some embodiments, the thickness of the stringer206is selected such that the stringer is configured to resist buckling under an axial load. For example, the stringers may have a material thickness that is sufficient to resist buckling when subjected to an axial load during a collision along the side of the tub101. In some embodiments, the stringers206may have a cross sectional profile that provides enhanced resistance to deformation under specific loading conditions (e.g., I-shape, T-shape, L-shape, U-shape, etc.). In some embodiments the cross section of the stringer206may vary along length214. In some embodiments, the stringers206are made from a high strength material (e.g., martensitic steel, other steels, alloys, composites, etc.) and may be formed by a property enhancing forming process such as roll forming. In other embodiments, the stringers206may be fabricated by a process such as extruding, press braking, stamping, forging, casting, or other similar or dissimilar forming and/or shaping processes. In some embodiments, stringers are formed using a sequence of forming and shaping processes (e.g., roll forming, punching, milling, cutting, etc.).

Referring toFIG. 6, a block diagram of a method300of manufacturing a battery enclosure (e.g., battery tub assembly100ofFIG. 1) is shown according to an exemplary embodiment. Notably, the steps can be altered or rearranged depending on methods of other embodiments. In an exemplary embodiment, a coating and/or coloring step may be included between steps of the method300.

At a step302, a metal tub (e.g. tub101) is formed, according to some embodiments. As part of step302, a metal sheet (e.g., a blank, a sheet metal, etc.) may be pressed into a die that forms the metal sheet into a tub shape. In an exemplary embodiment, the metal sheet is pressed (e.g., stamped, deep-drawn, etc.) into the tub shape shown inFIG. 2. In some embodiments, the metal sheet is pressed into a tub shape different than the tub shape shown inFIG. 2, according to other embodiments. In some embodiments, the wall104is integrally formed with the bottom102(e.g., is a single piece of material) and defines the internal volume106of the tub101.

In some embodiments, the method300includes pressing the workpiece (e.g. the metal sheet, sheet metal, blank, etc.) into successive dies to achieve the predetermined tub shape. In some embodiments, the method300includes stress relieving heat treatment to reverse the effects of work hardening between forming steps to restore ductility and workability to the tub material. For example, some or all of the tub101may require at least one heat treatment to prevent tearing or breaking the material during one or more stamping processes.

In some embodiments, the metal tub may be colored and/or coated using a method such as electrophoretic plating or powder coating to color and/or seal one or more surfaces of the tub (e.g., external surfaces, internal surfaces, etc.). The coating applied to the tub during coloring and/or coating may prevent deterioration (e.g., corrosion) of the tub material (e.g., metal). In some embodiments, the coating applied to the metal tub may facilitate or function as a barrier between the underlying material of the tub101(e.g., metal, steel, aluminum, etc.) and potential contaminates or corrosives associated with the internal volume106(e.g., inadvertently leaked electrolyte, water, fluids, etc.) or external environment (humidity, salt, debris, etc.).

At a step304, the metal tub is reinforced, according to some embodiments. The metal tub may be reinforced by the addition of stiffening features (e.g., stiffening features110, beading, corrugation, etc.) and/or by the addition of cross members (e.g., stringers206). The cross members may function as stringers and may be attached to the walls and bottom of the metal tub, as described in detail above.

At a step306, at least one mounting bracket (e.g. mounting bracket204) is added to the interior of the metal tub, according to some embodiments. The mounting brackets may be configured to releasably secure a battery (e.g., through a nut/bolt configuration) and are fixedly mounted (e.g., welded, bonded, fastened, etc.) to the interior surface of the metal tub. In some embodiments, the mounting brackets have threaded through-holes that are configured to receive a bolt with corresponding threading. In some embodiments, the mounting bracket204is welded or otherwise fixedly coupled to the tub101.

At a step308, at least one energy storage device (e.g. battery202, hydrogen fuel cell, etc.) is inserted into the internal volume of the metal tub, according to some embodiments. For example, at least one battery is mounted to at least one of the mounting brackets. For example, the battery may be releasably secured to the mounting bracket, as discussed above.

At a step310, a lid is sealed to the metal tub to thereby enclose and seal an internal volume (e.g., internal volume106) defined by the bottom (e.g., bottom102) and walls (e.g., wall104) of the metal tub, according to some embodiments. The lid may be sealed to the metal tub by a sealing method including the use of adhesives, fasteners, one or more gaskets, or any combination thereof.

In some embodiments, the manufacturing process may include several cold working processes, including several stamping (e.g., deep-drawing) processes. A primary stamping process may substantially form the walls and the bottom (see, e.g.,FIG. 1). Secondary or supplementary forming and/or shaping processes may be used to create additional features through processes such as beading, bulging, bottom piercing, ironing, necking, rib forming, side piercing, trimming, and/or curling. In an exemplary embodiment, the bottom of the tub includes stiffening features (e.g., stiffening beads, corrugation, ribbing, etc.) which enhance the structure and stiffness of the bottom and/or walls.

It is important to note that while operations inFIG. 6are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order or that all illustrated operations be performed to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. For example, the operations of step304and step306may be performed concurrently. Moreover, any separation of various components in the embodiments described above should not be understood as requiring such separation in all embodiments.

Although the FIGURES and description may illustrate a specific order of method steps, the order of such steps may differ from what is depicted and described, unless specified differently above. Also, two or more steps may be performed concurrently or with partial concurrence, unless specified differently above.

It is important to note that any element disclosed in one embodiment may be incorporated or utilized with any other embodiment disclosed herein. It should be appreciated that elements of the various embodiments may be incorporated or utilized with any of the other embodiments disclosed herein.