Magnesium integrated battery housing cum chassis

Abstract

The present disclosure relates to battery casing constituting a structural element of a chassis of a two-wheeler vehicle. The battery casing comprises a battery of the two-wheeler vehicle, and two enclosing sides for enclosing the battery of the two-wheeler vehicle, where the two enclosing sides are made of magnesium alloy and an exterior surface of each enclosing side comprises cooling fins for increasing surface area for cooling. The battery casing further comprises a plurality of self-tapping screws for joining the two enclosing sides, and one or more bolts for securing the battery casing to other structural elements of the two-wheeler vehicle. The battery casing and the other structural elements collectively constitute a structural chassis, and the battery casing acts as a load carrying member.

Description

MAGNESIUM INTEGRATED BATTERY HOUSING CUM CHASSISTECHNICAL FIELD

[0001] The present disclosure generally relates to automobile industry, and specifically relates to improving range provided by two-wheeler vehicles by optimising curb weight of the vehicleBACKGROUND

[0002] The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also correspond to implementations of the claimed technology.

[0003] Electric vehicles are becoming an increasingly popular segment of the automobile industry across the world, and electric two-wheelers contribute massively to the popularity of electric vehicles due to the many benefits and advantages provided. Some of the benefits accrued by users of electric two-wheeler vehicles include the low running cost, ease of maintenance, storage space, and low noise. In addition to the benefits provided to the users, electric vehicles are also environment-friendly as they do contribute to carbon emission.

[0004] Due to the increasing popularity of two-wheeler electric vehicles, there is an increasing need to optimize the performance of such vehicles. One such aspect of electric twowheeler vehicles that significantly impacts its performance, and requires improvement, is the curb weight of such vehicles. Due to the inherently small size of two-wheeler vehicles, there is limited battery capacity that is possible for electric two wheelers, and improvement in the range of electric two wheelers given such battery capacity limitations require reduction of curb weight of the vehicles.

[0005] The structural components of electric two-wheelers such as the chassis and battery encasing housed within the chassis are conventionally made from materials like steel and aluminium in the automotive industry. In existing technologies, the battery casings used for encasing the batteries used for powering the electric two-wheeler vehicles are aluminium casings. Further, the structural components such as the chassis are made with steel. Materials such as steel and aluminium contribute to the overall curb weight of vehicles, and thus negatively impact the range of electric two-wheeler vehicles.

[0006] Hence there is a need for developing a structural body for two-wheeler electric vehicles with reduction of curb weight that provides improved range and optimized batteryrange performance.OBJECT OF THE INVENTION

[0007] An obj ect of the invention is to create a battery housing mechanism for two-wheeler electric vehicles for achieving reduction in curb weight of such vehicles.

[0008] Another objective of the invention is to optimize range achieved by two-wheeler electric vehicles based on reduction of curb weight of the vehicles.

[0009] Yet another objective of the invention is to provide structural support to the twowheeler vehicle by incorporating the battery housing mechanism as a load-carrying member of the chassis of the two-wheeler vehicle.SUMMARY OF THE INVENTION

[0010] In general, embodiments of the present disclosure herein relates to a battery casing constituting a structural element of a chassis of a two-wheeler vehicle. Other implementations will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional implementations be included within this description be within the scope of the disclosure and be protected within the scope of the following claims.

[0011] In accordance with an embodiment of the present disclosure, battery casing constituting a structural element of a chassis of a two-wheeler vehicle is provided. The battery casing comprises a battery of the two-wheeler vehicle, and two enclosing sides for enclosing the battery of the two-wheeler vehicle, where the two enclosing sides are made of magnesium alloy and an exterior surface of each enclosing side comprises cooling fins for increasing surface area for cooling. The battery casing further comprises a plurality of self-tapping screws for joining the two enclosing sides, and one or more bolts for securing the batter casing to other structural elements of the two-wheeler vehicle, where the one or more bolts are attached to at least one of the two enclosing sides. The battery casing and the other structural elements collectively constitute the structural chassis of the two-wheeler vehicle, and the battery casing is used as a load carrying member of the two-wheeler vehicle. Further, the battery is enclosed between the interior surfaces of the two-enclosing sides.

[0012] In one aspect, the magnesium alloy is AZ91D, which is a high-purity magnesium die casting alloy having low density, high yield strength, and suitable for high pressure die casting process. In another aspect, the mechanical properties of the AZ91D magnesium alloy used for the battery casing include an ultimate tensile strength of 240 MPa, yield strength of 160 MPa, elongation 3-5%, hardness of 70 Brinell, elastic modulus of 45 GPa, and Charpy impact of 6 J.

[0013] In one aspect, the physical properties of the AZ91D magnesium alloy used for the battery casing include density of 1.81 g / cm3, melting range of 435-598 C, specific heat of 1.02 kJ / kg k, coefficient of thermal expansion of 26 um / m - k, thermal conductivity of 51 (W / m- k), electrical conductivity of 6.60 MS / m, and corrosion rate of 0.05 mg / cm2 / day.

[0014] In another aspect, the exterior surface of each enclosing side is coated with a combination of Alodine 5200, CED (Cathodic Electrodeposition) layer, and powder coat to enhance paint adhesion and improve corrosion resistance in the magnesium allow of the battery casing.

[0015] In another aspect, the one or more bolts are made from steel, and Nylon 11 coating is provided to the one or more bolts to act as an insulating barrier that physically separates the one or more bolts from the battery casing, and prevents direct electrical contact and breaks galvanic circuit.

[0016] In another aspect, the self-tapping screws create their own threads, and eliminated need for drilling the battery casing.

[0017] In another aspect, the other structural elements include rear suspension, front suspension, and a frame. In yet another aspect, the battery casing is directly connected with a motor, the front suspension, the frame, and a rider footrest of the two-wheeler vehicle.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings constitute a part of the description and are used to provide further understanding of the present disclosure. Such accompanying drawings illustrate the embodiments of the present disclosure which are used to describe the principles of the present disclosure. The embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and they mean at least one. In the drawings:

[0019] Fig. 1(a) and 1(b) illustrate perspective views of the magnesium battery casing, in accordance with an embodiment of the present invention; and

[0020] Figs. 2(a) and 2(b) illustrate perspective views of the magnesium battery casing constituting a structural element of the chassis of the electric two-wheeler vehicle, in accordance with an embodiment of the present invention.DETAILED DESCRIPTION OF THE INVENTION

[0021] The description that follows describes, illustrates and exemplifies one or more particular embodiments of the invention in accordance with its principles. This description is not provided to limit the invention to the embodiments described herein, but rather to explain and teach the principles of the invention in such a way that enables one of ordinary skill in the art to understand these principles and, with that understanding, be able to apply them to practice not only the embodiments described herein, but also other embodiments that may come to mind in accordance with these principles. The scope of the invention is intended to cover all suchembodiments that may fall within the scope of the appended claims, either literally or under the doctrine of equivalents.

[0022] It should be noted that in the description and drawings, like or substantially similar elements may be labelled with the same reference numerals. However, sometimes these elements may be labelled with differing numerals, such as, for example, in cases where such labelling facilitates a clearer description. Additionally, the drawings set forth herein are not necessarily drawn to scale, and in some instances, proportions may have been exaggerated to more clearly depict certain features. Such labelling and drawing practices do not necessarily implicate an underlying substantive purpose. As stated above, the specification is intended to be taken as a whole and interpreted in accordance with the principles of the invention as taught herein and understood to one of ordinary skill in the art.

[0023] As used herein, the term “comprising” means including but not limited to and should be interpreted in the manner it is typically used in the patent context. Use of broader terms such as comprises, includes, and having should be understood to provide support for narrower terms such as consisting of, consisting essentially of, and comprised substantially of.

[0024] The phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” and the like generally mean that the particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present disclosure, and may be included in more than one embodiment of the present disclosure (importantly, such phrases do not necessarily refer to the same embodiment).

[0025] The word “example” or “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations.

[0026] Electric automobiles, especially two-wheeler vehicles have been growing in popularity and demand due to the several benefits and advantages offered by such vehicles. However, optimization of performance of two-wheeler vehicles has been a persistent issue due to the limited battery capacity that can be provided in such vehicles. Hence optimization of performance of such vehicles, especially with regard to the range achieved by such vehicles, is only possible with optimizing the battery capacity to range ratio of the vehicles. The rangeoffered by an electric vehicle with a given battery capacity can be improved by improving the structural aspects and curb weight of the vehicle, so as to reduce the energy required for powering the acceleration or propulsion of the vehicles.

[0027] The curb weight of a vehicle plays a significant role in the energy required for the acceleration or propulsion of an electric vehicle, and thereby the energy to be provided by the battery of the electric vehicle for its acceleration. Decreasing the curb weight of the vehicle is the easiest way to increase the energy economy of electric vehicles without having to increase the battery capacity of such vehicles. The structural components of the electric two-wheeler vehicles, especially the chassis of the two-wheeler vehicle and the battery casing that is housed within the chassis, contribute significantly to the curb weight of the vehicle. Hence modification of structural aspects of such components are performed in the proposed invention to achieve reduced curb weight and increased range of electric two-wheelers

[0028] The present invention relates to a magnesium integrated battery casing (or housing) used as a chassis member in electric two-wheeler vehicles. The present invention comprises a battery housing made of magnesium which is used as a structural part of the chassis in the electric two-wheeler vehicles. In addition to constituting a structural part of the chassis, the magnesium battery casing is also used as a load carrier member of the electric two-wheeler vehicle.

[0029] Fig. 1(a) and 1(b) illustrate perspective views of the magnesium battery casing, in accordance with an embodiment of the present invention. The magnesium battery casing 100 constitutes a structural element of a chassis of a two-wheeler vehicle. The magnesium battery casing 100 comprises a battery of the two-wheeler vehicle, a first enclosing side 102-a and a second enclosing side 102-b, a plurality of self-tapping screws 104-a to 104-n (collectively labelled 104) for joining the two enclosing sides, and one or more bolts 106-1 to 106-n (collectively labelled 106). The first enclosing side 102-a and the second enclosing side 102-b are hereafter collectively referred to as enclosing sides 102. The enclosing sides 102 are made of magnesium alloy, are used for enclosing the battery of the two-wheeler vehicle. Specifically, the interior surfaces of the enclosing sides 102 are used for enclosing the battery. The exterior surface of the enclosing sides 102 comprise cooling fins for increasing surface area for heat dissipation, thereby improving cooling.

[0030] Fins effectively increase the surface area of a heat transfer component, allowing for more efficient heat dissipation or absorption. With a larger surface area, fins facilitate a higher rate of heat transfer between the solid surface and the surrounding fluid. Fins help dissipate heat more effectively, leading to better cooling of components and systems, thus preventing overheating and maintaining optimal operating temperatures. Fins allow for improved heat transfer without significantly increasing the size or volume of the heat transfer component or system, making them ideal for compact designs where space is limited. Hence, in an embodiment of the present invention, fins are provided on exterior surface of the enclosing sides 102 of the magnesium battery casing 100 for better thermal performance.

[0031] The plurality of self-tapping screws 104 are used in magnesium battery housing 100 to seal or join the enclosing side 102 of the magnesium battery casing 100. They create their own threads as they are driven into the material, resulting in a secure and tight connection. Unlike traditional screws, the self-tapping screws 104 are less likely to cause splitting or damage to the material. By eliminating the need for separate drilling operations, they can reduce overall manufacturing costs. Their self-drilling nature makes them ideal for automated assembly processes, improving efficiency in mass production environments.

[0032] The self-tapping screws 104 create their own threads as they are driven into the material, which means they do not rely on pre-existing threads. This reduces the risk of thread wear and stripping in casting alloys. The process of tapping the material as the screw is inserted can actually strengthen the material around the threads, providing a more durable and lasting hold. Self-tapping screws 104 eliminate the need for pre-drilling or tapping, saving time and effort during assembly. This can be particularly useful in mass production or field applications. Since the self-tapping screws 104 do not require separate taps or dies, fewer tools are needed, simplifying the toolkit and reducing costs. Further, the self-tapping screws 104 often provide a more secure fit than traditional screws, and provide a robust solution to avoid thread wear in casting materials by creating their own threads and reinforcing the material during installation. They simplify the assembly process, provide strong and lasting connections, and are versatile across various applications.

[0033] The one or more bolts 106 are used for securing the magnesium battery casing 100 to other structural elements of the two-wheeler vehicle, and are attached to at least one of the enclosing sides 102 to enable securing of the magnesium battery casing with the other structuralelements. The other structural elements of the two-wheeler vehicle may include one or more of: rear suspension, front suspension, and a frame. In one embodiment, the one or more bolts 106 may be made of steel. The magnesium battery casing 100 forms a part of the chassis based on its securing to the other structural elements, and hence constitutes a load carrying member of the two-wheeler vehicle. In one embodiment, the magnesium battery casing is directly connected with a motor, the front suspension, a frame, and a rider footrest of the two-wheeler vehicle.

[0034] The magnesium battery housing 102 is made of magnesium since it is lighter in weight as compared to materials such as aluminium and steel that are conventionally used for creating battery casing and chassis of two-wheeler vehicles. Use of magnesium ensures that a target curb weight requirement for optimizing the range achieved by the electric two-wheeler vehicle. The reduced density of magnesium as compared to materials such as steel and aluminium ensures curb weight is efficiently reduced. The magnesium battery housing 102 is used as a structural member of the chassis of the electric two-wheeler vehicle in which it is utilized, and helps increase the range without compromising the strength and durability of the structure of the two-wheeler vehicle.

[0035] Not only is magnesium light-weight, durable, and stronger than aluminium, but it also absorbs more shock and vibrations, making it the ideal metal for two-wheeler vehicles that may be used in competitive sports. Magnesium alloys tend to have a high strength-to-weight ratio, exceptional machinability. They have a low specific gravity of 1.74 g / cm3 and a relatively low Young’s modulus (42 GPa) compared to other common alloys such as aluminium or steel alloys Low density, -1.74 g / cm3 in combination with relatively a high tensile strength of 228-290 MPa, heat resistance up to 450°C, and oxidation resistance up to 500°C.

[0036] In one embodiment of the present invention, the material used for the battery housing is AZ91D which is a specific alloy of the magnesium, which has low density and high yield strength and is much feasible for the high pressure die casting process. The following mechanical and physical properties made to choose the specific alloy the battery housing:

[0037] It is clear that the Ultimate tensile strength is 240 Mpa which is adequate at best in comparison with the other magnesium alloy and comparatively equal with the aluminium alloy which helps us in mainly more strength as structural members. In addition, the Elongation is very less and similar when compared with the aluminium. From the physical properties it is clear the alloy corrosion rate is very less 0.05mg / cm2 / day means the alloys chosen is corrosion resistant and the coefficient of thermal expansion is 26 (um / m - k), which say the material is most sufficiently equipped with the thermal resistance.

[0038] The AZ91D is a high-purity magnesium die casting alloy. Magnesium as a metal has poor corrosion resistance. However, the AZ91D alloy exhibits excellent resistance against corrosion. The corrosion resistance is achieved by introducing aluminium and strictly controlling the percentage of iron, nickel, and copper in it. Hence, it is a good alternative to aluminium die casting alloys. The rest of the characteristics of AZ91D alloy is similar to that of primary magnesium metal. Its density is significantly less than aluminium and zinc.

[0039] The AZ91D has a wide range of applications in various industries. The aerospace industry uses this alloy in non-structural components like engine and transmission parts. The automotive industry uses magnesium parts in chassis, gearbox housing, interior components, etc. Alloy AZ91D is the most widely-used magnesium die casting alloy. It is a high-purity alloy with excellent corrosion resistance, excellent castability, and excellent strength. Corrosion resistance is achieved by enforcing strict limits on three metallic impurities: iron, copper and nickel. Ductility increases at the expense of castability and strength, as aluminium contentdecreases. Therefore, the alloy with the lowest aluminium content will meet the application requirements.

[0040] The high-purity alloy offers good corrosion resistance for your magnesium parts. It also provides greater wear resistance, higher temperature resistance, and better energy absorption / impact resistance characteristics. Compared to steel, magnesium is 75% lighter with no significant loss of strength. It is a far better material for complex, thin-walled, net shape or near-net shape castings and offers greater dimensional stability. Magnesium castings can meet tight tolerances that would be difficult or impossible to achieve with steel. Tooling costs can be lower for magnesium castings, as multiple parts can be easily consolidated into a single component. This also improves component rigidity and reduces welding and assembly costs.

[0041] Compared to aluminium, magnesium is 33% lighter, with similar or improved mechanical properties, and machines easier. Magnesium provides greater corrosion resistance, and is better suited to large, thin-wall, net shape complex parts. In addition, the exterior surface of the magnesium battery casing 100, exposed to weather, UV and stone chips is coated by a coating process. The coating process involved coating using Alodine 5200 + CED layer + Powder coat. The Alodine 5200 coating used in the present application is designed to enhance paint adhesion and improve corrosion resistance in magnesium. This product is especially relevant for applications like Cathodic Electro Deposition and powder coating, where it creates a thin, protective layer on the surface. This layer acts as a barrier, reducing the direct exposure of the metal to environmental factors that cause corrosion, such as moisture and oxygen. Alodine 5200 ensures that these coatings are more durable and less likely to chip or peel. This enhanced adhesion contributes to the overall corrosion resistance because the coatings stay intact longer, protecting the underlying metal from corrosive elements and has a microcrystalline structure that is highly resistant to corrosion. This structure can fill micro-voids and imperfections on the metal surface, which are potential sites for corrosion initiation.

[0042] When one or more bolts 106, made of steel, are mounted on a magnesium casing, the contact between these dissimilar metals in the presence of water can lead to galvanic corrosion. This type of corrosion occurs because magnesium has different electrochemical potentials, with magnesium being more anodic. In a galvanic couple, the anodic material magnesium corrodes preferentially. To mitigate this, coating like Nylon 11 to act as a barrier is applied on the one or more bolts 106, in an embodiment. The Nylon 11 coating acts as aninsulating barrier that physically separates the steel bolts from the magnesium casing, preventing direct electrical contact and thereby breaking the galvanic circuit. This interruption stops the flow of electrons between the two metals, which is necessary for galvanic corrosion to occur. It maintains its protective properties in a wide range of temperatures and humidity levels. Nylon 11 is tough and resilient, providing long-lasting protection even under mechanical stress. It has good flexibility, which helps it maintain a protective seal even if there are slight movements or thermal expansions / contractions in the materials.

[0043] Further, Nylon 11 coating to the one or more bolts 106 mounted on a magnesium battery casing 100 effectively prevent galvanic corrosion by insulating the two metals from direct electrical contact, blocking moisture and other corrosive elements from reaching the metal surfaces and providing durable, long-lasting protection that withstands environmental and mechanical stresses. This approach ensures the longevity and integrity of the assembly, preventing corrosion-related failures and maintaining the functionality of the components.

[0044] Such technical features of the components of the magnesium battery casing 100 enables achieving a reduced curb weight, and providing structural support based on use of the magnesium battery casing 100 as a load bearing structure of the two-wheeler vehicle. Figs. 2(a) and 2(b) illustrate perspective views of the magnesium battery casing constituting a structural element of the chassis of the electric two-wheeler vehicle, in accordance with an embodiment of the present invention. As illustrated in Figs. 2(a) and 2(b), the magnesium battery casing 202 is secured to the structural elements (collectively labelled 204) of the twowheeler vehicle by the one or more bolts 206, and along with the structural elements constitute a structural chassis, and aids in the load carrying capability of the structural chassis. Hence the magnesium battery casing proposed in the present invention acts as a battery enclosure for the battery powering the electric two-wheeler vehicle and also acts as a structural member of the chassis of the two-wheeler vehicle used for providing structural reinforcements and strength.

[0045] The battery housing or enclosure mechanism proposed in the present invention hence helps in effectively reducing the curb weight of electric two-wheeler vehicles by replacing conventional aluminium or steel based structural aspects with components such as magnesium battery housing, which results in a reduced curb weight due to the lower density of magnesium. The reduction of the curb weight in such vehicles helps optimize the range achieved by the vehicles. Further, the inherent nature of the magnesium enables betterabsorption of shocks and vibrations. Additionally, use of Nylon 11 coatings and application of fins in embodiments of the present invention allows for improved protection from corrosion and better thermal performance respectively.

[0046] Any combination of the above features and functionalities may be used in accordance with one or more embodiments. In the foregoing specification, embodiments have been described with reference to numerous specific details that may vary from implementation to implementation. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. The sole and exclusive indicator of the scope of the invention, and what is intended by the applicants to be the scope of the invention, is the literal and equivalent scope of the set as claimed in claims that issue from this application, in the specific form in which such claims issue, including any subsequent correction.

Claims

We claim:

1. A battery casing constituting a structural element of a chassis of a two-wheeler vehicle, the battery casing comprising: a battery of the two-wheeler vehicle; two enclosing sides for enclosing the battery of the two-wheeler vehicle, the two enclosing sides are made of magnesium alloy and an exterior surface of each enclosing side comprises cooling fins for increasing surface area for cooling; a plurality of self-tapping screws for joining the two enclosing sides; and one or more bolts for securing the battery casing to other structural elements of the twowheeler vehicle, wherein the one or more bolts are attached to at least one of the two enclosing sides, wherein the battery casing and the other structural elements collectively constitute the chassis of the two-wheeler vehicle; wherein the battery casing is used as a load carrying member of the two-wheeler vehicle; and wherein the battery is enclosed between interior surfaces of the two enclosing sides.

2. The battery casing as claimed in claim 1, wherein the magnesium alloy is AZ91D, which is a high-purity magnesium die casting alloy having low density, high yield strength, and suitable for high pressure die casting process.

3. The battery casing as claimed in claim 2, wherein the mechanical properties of the AZ91D magnesium alloy used for the battery casing include an ultimate tensile strength of 240 MPa, yield strength of 160 MPa, elongation 3-5%, hardness of 70 Brinell, elastic modulus of 45 GPa, and Charpy impact of 6 J.

4. The battery casing as claimed in claim 2, wherein the physical properties of the AZ91D magnesium alloy used for the battery casing include density of 1.81 g / cm3, melting range of 435-598 C, specific heat of 1.02 kJ / kg k, coefficient of thermal expansion of 26 um / m - k, thermal conductivity of 51 (W / m-k), electrical conductivity of 6.60 MS / m, and corrosion rate of 0.05 mg / cm2 / day.

5. The battery casing as claimed in claim 1, wherein the exterior surface of each enclosing side is coated with a combination of Alodine 5200, CED (Cathodic Electrodeposition) layer, and powder coat to enhance paint adhesion and improve corrosion resistance in the magnesium allow of the battery casing.

6. The battery casing as claimed in claim 1, wherein the one or more bolts are made from steel.

7. The battery casing as claimed in claim 6, wherein Nylon 11 coating is provided to the one or more bolts to act as an insulating barrier that physically separates the one or more bolts from the battery casing, and prevents direct electrical contact and breaks galvanic corrosion.

8. The battery casing as claimed in claim 1, wherein the self-tapping screws create their own threads, and eliminated need for drilling the battery casing.

9. The battery casing as claimed in claim 1, wherein the other structural elements include rear suspension, front suspension, and a frame.

10. The battery casing as claimed in claim 1, wherein the battery casing is directly connected with a motor, the front suspension, the frame, and a rider footrest of the two-wheeler vehicle.

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