Manufacturing method for a frame structure for a motor vehicle, and large-scale cast part, system and vehicle

Abstract

The invention relates to the manufacture of load-bearing motor vehicle parts by means of a large-scale casting process, not aiming for the maximum reduction in the number of parts but pursuing instead a modular design concept and providing a plurality of alternative parts that can be combined in different ways. In this way, large-scale casting technology can also be used in a cost-effective manner for modular product line concepts, by using various large-scale cast parts in different combinations depending on the model.

Description

[0001] Description

[0002] Manufacturing process for a frame structure for a motor vehicle

[0003] The invention relates to a manufacturing method for a frame structure for a motor vehicle, an upper large cast component for a motor vehicle, a lower large cast component for a motor vehicle, a system consisting of an upper large cast component and a lower large cast component, a modular system and a motor vehicle.

[0004] In recent years, the use of large cast components in vehicle manufacturing has increased. A large cast component in a motor vehicle is typically a large, single-piece part produced by casting a metal or metal alloy into a mold. These components are playing an increasingly important role in the automotive industry because they enable complex structures with high strength and stability. The trend toward producing larger parts of the vehicle structure in a single casting is particularly evident in electric vehicles, as large cast components offer advantages over conventional manufacturing methods, including higher precision, a reduced number of welds (which increases stiffness and reduces weight), and cost-efficiency in mass production. The use of these components can therefore help make vehicles lighter, safer, and more efficient.

[0005] A disadvantage of using large cast components is that they introduce large and expensive parts into a vehicle's design. The larger the components become, the more expensive and larger the tooling required for their production. On the other hand, large casting technology significantly reduces the number of parts in a steel body shell. However, in the event of damage, repairs can be very complex and, in extreme cases, uneconomical, as smaller components cannot be replaced; instead, the entire large cast component—for example, a complete front or rear section—must be replaced. Due to the high tooling costs, profitability also depends heavily on the production volume.For models with smaller planned or expected production quantities, the use of large-scale casting technology, as currently employed according to the state of the art, is therefore often not worthwhile.

[0006] German patent DE 102021 206369 A1 discloses a method for assembling a motor vehicle body that simplifies manufacturing in the front end area. The method involves pre-assembling the front end structure separately from the body section, with the separation occurring directly in front of or behind the bulkhead. This enables more efficient pre-assembly and simplifies the use of large-area components for the bulkhead, ideally in one piece. The bulkhead can be manufactured from a flat semi-finished product using a forming process, which also allows the use of different steel grades and thicknesses to selectively influence its properties.

[0007] US Patent 2023 / 0373563 A1 describes an integrated energy absorption system for vehicles, consisting of single-cast metal parts. The system includes front and rear castings, each incorporating wheel wells, bumper mounts, and crumple zones. The castings feature rib structures that can be configured in "I," "C," or closed shapes to ensure progressive deformation upon impact. Various techniques, such as cutouts, wave profiles, tapers, and rib spacing, are employed to optimize energy absorption and improve mass efficiency.

[0008] German patent DE 102021 212918 A1 describes a method for repairing large cast components in motor vehicles, such as those used in the body structure. Instead of replacing the entire component, only the damaged section is cut out and replaced with a custom-made spare part. This spare part is manufactured using an additive manufacturing process, such as selective laser melting (SLM), and features special interfaces that allow it to be joined to the large cast component. To simplify the repair process, predefined separation points are marked on the large cast component, enabling the use of standardized spare parts.

[0009] The object of the present invention is therefore to provide a way to make the advantages of large casting technology economically usable for a wider range of motor vehicle models.

[0010] The task is solved by a manufacturing process for a frame structure for a motor vehicle, comprising the steps:

[0011] a. Selection of a first large cast component from a modular system containing a plurality of different large cast components,

[0012] b. Selection of at least one second large cast component from the modular system, wherein the second large cast component has an interface for connecting to the first large cast component, and

[0013] c. Joining the first large cast component to the second large cast component.

[0014] The problem is further solved by an upper large cast component for a motor vehicle with at least one upper longitudinal member element, wherein the large cast component is designed to be connected to at least one lower large cast component for a motor vehicle, and wherein the at least one lower large cast component has at least one lower longitudinal member element, as well as by a lower large cast component for a motor vehicle with at least one lower longitudinal member element, wherein the large cast component is designed to be connected to at least one upper large cast component for a motor vehicle, and wherein the at least one upper large cast component has at least one upper longitudinal member element.

[0015] Furthermore, the task is solved by a system consisting of such an upper large cast component and such a lower large cast component, by a modular system comprising at least one lower large cast component for a frame structure for a motor vehicle and a plurality of alternative upper large cast components for the frame structure, each connectable to the lower large cast component, as well as by a motor vehicle with an upper large cast component of the aforementioned type, with a lower large cast component of the aforementioned type or with a system of the aforementioned type.

[0016] In summary, the proposal aims to manufacture load-bearing automotive components using large-scale casting processes, but without striving for maximum component reduction. Instead, it seeks a modular approach and provides several alternative components that can be combined in various ways. This allows large-scale casting technology to be used cost-effectively for modular model series concepts by employing different large-scale cast components in varying combinations depending on the model.

[0017] For the purposes of this description, a frame structure is understood to mean, in particular, the load-bearing framework of a motor vehicle that absorbs and distributes the main loads and forces during operation. The frame structure serves to connect and support the various components such as the engine, transmission, body, and chassis. In the context of a known monocoque structure, the frame structure can, in particular, comprise longitudinal beams and cross members. For the purposes of this description, a modular system is understood to mean, in particular, a system of standardized and interchangeable modules or components, several of which can be combined with one another. At least one element of the modular system can alternatively be combined with at least two other elements of the modular system.The simplest example of such a modular system would be a kit containing three elements, one of which is a basic element that can be combined with either of the other two elements. These modules or elements can be combined in various configurations to create different vehicles or variants of a vehicle, such as different body styles.

[0018] In the context of this description, an interface is understood to be, in particular, a connection point between two components where the components are joined by force-fit, form-fit, or material-fit methods. This mechanical interface serves, in particular, to transmit forces and moments between the components and ensures that they function together as a single unit.

[0019] In the context of this description, a longitudinal beam element is understood to be, in particular, an essential component of the vehicle's supporting structure.

[0020] This structure runs longitudinally along the vehicle and usually on both sides of the frame or body. The longitudinal member serves to absorb the forces that occur during driving, braking, or in a collision and distribute them evenly across the entire vehicle structure. Typically, the longitudinal member extends from the front axle to the rear axle and is integrated either into the body (in monocoque constructions) or into the vehicle frame (in ladder frame constructions).

[0021] According to the invention, it has been recognized that the use of monolithic large-cast components also entails disadvantages. Firstly, these can occur in the maintenance or repair situations described above. Secondly, it has also been recognized that the use of a large-cast front or rear section also results in reduced flexibility in the further design of the motor vehicle.

[0022] Small production runs are often not economically viable with this technology, as the acquisition costs for the necessary tooling would constitute too large a portion of the total costs. The invention addresses this with a modular approach: A large cast component, which could theoretically be manufactured as a single unit, is divided into several large cast components for each individual vehicle model to increase flexibility and reduce tooling costs. These components are then joined together to form, for example, a front end or a rear end. This approach deliberately forgoes a fundamental advantage of large-scale casting technology, namely the maximum reduction in the number of components. However, it achieves significantly increased flexibility, which, depending on the model, can translate into considerably reduced production and repair costs.

[0023] For vehicles intended for mass production without body variations, it is therefore advantageous to use as few large components as possible, which corresponds to maximally integrated components. However, if the project approach involves a so-called platform / hat concept, for example, if different body variants such as hatchback, station wagon / estate, or coupe are to be realized with a common underbody, it is often advisable to forgo maximum integration in favor of a more flexible approach. A model-specific "hat" refers in particular to a specific body shape or other specific structure, whereby different "hats" are compatible with the same basic platform, which may include, for example, a chassis and a powertrain.This allows for maximum flexibility in the platform design, for example, regarding vehicle length, width, and height, wheelbase, track width, body shapes, etc., while maintaining the highest level of integration of platform-specific features such as the mounting points for engine and chassis components, the battery, etc. Further advantages include cost reduction through interchangeable components in large castings, which can also lead to a lower insurance classification for the end customer. Damage to very large components, such as a large-cast front end or rear end, results in very high costs, which can quickly lead to a total loss.While a higher number of smaller components requires slightly more assembly effort during production, it offers customers and insurers greater financial security in the event of accidents, which can positively impact the sales price and insurance classification. Furthermore, the individual tools and machines used to manufacture the large cast components become smaller and therefore less expensive in terms of production, operation, transport, and maintenance.

[0024] Separating the large cast components allows for the integration of additional functional features that would often be impossible in a very large tool, for example, because tool slides cannot be installed or cooling systems cannot be relocated within the tool. This also enables the production of components with higher precision overall. The resulting tighter tolerances then lead to higher-quality products. Furthermore, the clever design of the large cast components with common interfaces increases the flexibility of drive concepts. This allows for the implementation of pure BEVs (Battery Electric Vehicles), as well as hybrid and other vehicle concepts, all on the same overall platform. Only individual large cast components need to be specifically designed for this purpose. A complete redesign of the entire large cast component and the production of a separate, large tool are then often unnecessary.

[0025] A key aspect of the invention is that the components each have interfaces through which they can be connected to various other components. This makes it possible to produce a large number of different vehicle models using large-scale casting technology with relatively few different components. A modular design approach can be applied. For example, a lower base component, which is identical for several vehicle models and has connection points for the chassis, can be connected to one or more different upper base components. Depending on the lower base component or the upper base components, various body styles such as hatchback, convertible, and SUV (Sports Utility Vehicle) can then be achieved.For each of these body styles, which may be based on identical or similar chassis, there is no need to maintain a dedicated tool for manufacturing, for example, the entire large cast front end. Instead, several body variants "share" the tools used to produce large cast components used in multiple body styles.

[0026] For example, a large cast front section can be manufactured, consisting of several components. These components could be, for instance, a lower section and an upper section, a lower section, an upper left section, and an upper right section, or a lower section, an upper left section, an upper right section, and another section, such as a large cast bulkhead. Analogous possibilities exist for a large cast rear section or for other elements of the frame structure. Naturally, the respective lower section can also be designed in multiple parts, for example, as a lower right section and a lower left section.

[0027] The individual components can be designed to be interconnected. These components can have interfaces for connecting to other components, and according to the modular principle, several components that perform the same function in different vehicle models can have similar or identical interfaces. For example, the interface of an upper left cast front section for a sedan can be the same as that of an upper left cast front section for a convertible. Both models can then, for instance, use the same lower cast front section.

[0028] The individual elements can be separated or connected along different directions. In principle, it is conceivable that the interfaces or connecting surfaces between individual elements run along the X-direction, the Y-direction, or the Z-direction. It is possible that the specific course of the interface or connecting surface does not exactly correspond to the stated direction or plane. For example, a compensating plane running through the separating surface or interface may form an angle of, for example, less than 20° or less than 10° with a plane that is perpendicular to the X-direction, the Y-direction, or the Z-direction. The X-direction refers specifically to the longitudinal direction of the vehicle or the direction of travel, the Y-direction to the transverse direction of the vehicle, and the Z-direction to the vertical.

[0029] Hybrid forms are also conceivable, in which the interface runs proportionally in the X-direction, the Y-direction, and / or the Z-direction. A three-dimensional shape for the interface or connection surface is also possible.

[0030] In a preferred embodiment, the upper and lower large casting components are designed to form a positive-locking connection with each other. The same applies to other large casting components, for example, a left and a right large casting component, or a front and a rear large casting component.

[0031] Furthermore, it is possible that the upper large cast component and the lower large cast component are designed to be welded or bonded together.

[0032] Naturally, these connection methods are not limited to "upper" and "lower" large cast components, but can be applied to all large cast components of the modular system. Likewise, it is of course possible to provide interfaces for other elements that are not part of the modular system, for example, elements not manufactured using the large cast process. It is possible for the lower large cast component to be designed to be connected to at least two other large cast components. It is also possible for the lower large cast component to be designed to be connected to one other large cast component, and for the upper large cast component to be designed to be connected to the other large cast component. In other words, it is possible for a total of at least three or at least four large cast components to be connected to one another.In this process, at least one of the components can be connected to several other components, for example to two other components.

[0033] It has been found that dividing a component manufactured using known large-scale casting processes into two to four separate components is sufficient in most cases to achieve the desired flexibility in the design of the vehicle.

[0034] A modular system encompassing a number of vehicle models can contain a total of at least 5 elements, at least 10 elements, or at least 15 elements, in other words, large cast components.

[0035] All descriptions relating to a “lower” large casting element and an “upper” large casting element and their interaction are of course also applicable to large casting elements that are not explicitly an upper or lower large casting element.

[0036] Exemplary embodiments of the invention are explained in more detail with reference to the drawings and the following description. The drawings show:

[0037] Fig. 1: a schematic side view of a motor vehicle according to the invention, Fig. 2: a schematic perspective view of a part of a frame structure according to the invention in the form of a first embodiment of an upper large cast component according to the invention,

[0038] Fig. 3: shows a schematic perspective view of part of a frame structure according to the invention in the form of a first embodiment of a lower large cast component according to the invention,

[0039] Fig. 4: a schematic representation of a front end constructed using the modular system according to the invention and using large cast components according to the invention, and

[0040] Fig. 5: A schematic perspective view of a frame structure 6 of a motor vehicle according to the invention. Figure 1 shows a schematic side view of a motor vehicle 2 according to the invention. The motor vehicle 2 has a body 4, under which a frame structure 6, shown only schematically, is arranged. This frame structure 6 functions as a load-bearing component of the motor vehicle 2 and is manufactured from the modular system according to the invention by selecting several large cast components.

[0041] Figure 2 shows a schematic perspective view of a portion of a frame structure according to the invention in the form of a first embodiment of an upper large cast component 8 according to the invention. The upper large cast component 8 has an upper longitudinal member 12 and a spring dome 14 on both the left and right sides. The firewall 16 is arranged in a central area facing the vehicle interior. The underside of the upper large cast component 8 is designed as a lower interface 34, so that the upper large cast component 8 can be connected to at least one lower large cast component (not shown in the figure). The lower interface 34 is designed such that a positive-locking connection can be established with the respective lower large cast component. Additionally, a further connection, such as a welded or adhesive bonded joint, can be provided.

[0042] Figure 3 shows a schematic perspective view of a portion of a frame structure according to the invention in the form of a first embodiment of a lower cast component 10 according to the invention. The lower cast component has a lower longitudinal member 18 on both the left and right sides. The upper surface of the lower cast component 10 is designed as an upper interface 36, so that the lower cast component 10 can be connected to at least one upper cast component (not shown in the figure), for example, the upper cast component from Figure 2. The upper interface 36 is designed such that a positive-locking connection with the respective upper cast component can be established.

[0043] The upper interface 36 can be designed to be complementary in shape to the lower interface of the associated upper large casting component. It is therefore possible to construct the lower large casting component 10 and the associated upper large casting component by making a suitable cut or a suitable parting line through a conventional large casting component. The parting line can, for example, run predominantly horizontally. It is also possible to provide several such cuts or parting lines, so that the conventional large casting component is divided into more than two elements, for example, into three, four, five, or more elements.The terms "section" and "parting surface" are used figuratively to mean that a single, unified component is not first produced and then separated into several components. Instead, the component is initially designed as a single piece, like a conventional large-scale cast component, and then the boundaries between the individual components are designed and defined. The individual components are then produced from the outset as separate parts using their own tooling.

[0044] Figure 4 shows a schematic representation of a front section 42, which was manufactured using the modular construction system according to the invention and using large cast components according to the invention. The front section 42 essentially consists of four elements: the lower large cast component 10, the upper left large cast component 38, the upper right large cast component 40, and a further large cast component 20 in the form of a water tank. The aforementioned elements are designed to be coordinated with one another such that, when assembled, they are in contact with each other via large connecting surfaces. The water tank 20 is also manufactured using large cast construction. A water deflector 22 is additionally arranged at the upper edge of the water tank 20.The arrow indicates the intended assembly direction, in which the lower large cast component 10 forms the base and the other three large cast components 20, 38 and 40 are placed on top of the lower large cast component 10 from above, in other words in the Z direction.

[0045] The lower large cast component 10 has a lower longitudinal beam element 18 on both its left and right sides. The upper left large cast component 38 and the upper right large cast component 40 each additionally have an upper longitudinal beam 12, which, when assembled, joins with the respective lower longitudinal beam 18 to form a fully functional longitudinal beam. It is evident that, according to the invention, the separation of the conventionally manufactured one-piece component can also be achieved such that traditionally manufactured one-piece elements, such as a longitudinal beam of a conventional frame structure, are divided into several large cast components.In other words, an interface between a first large-cast component, for example a lower large-cast component, and a second large-cast component, for example an upper large-cast component, can run through a functional element, such that portions of this functional element, for example a longitudinal beam, are present in both large-cast components. Several large-cast components can thus have portions of the functional element. It can also be seen in Figure 4 that the lower large-cast component 10 is connected to the side wall module 24. The lower large-cast component 10 therefore has another interface for a component not manufactured using the large-casting process.

[0046] Figure 5 shows a schematic perspective view of a frame structure 6 of a motor vehicle according to the invention. The frame structure 6 comprises a front section 42 and a rear section 26, both constructed using the modular system according to the invention. The rear section 26 consists of three large cast components: the cross member 28, the left wheel arch 30, and the right wheel arch 32. Other numbers and shapes of large cast components for constructing the rear section 26 are, of course, also possible. (List of reference numerals)

[0047] motor vehicle

[0048] body

[0049] framework structure

[0050] upper large cast component

[0051] lower large cast component

[0052] upper longitudinal beam

[0053] Spring dome

[0054] firewall

[0055] lower longitudinal beam

[0056] Water collection box

[0057] Water catcher strip

[0058] Side wall module

[0059] Rear end

[0060] crossbeam

[0061] left wheel arch

[0062] right wheel arch

[0063] lower interface

[0064] upper interface

[0065] upper left large cast component

[0066] upper right large cast component

[0067] front end

Claims

Patent claims 1. Manufacturing process for a frame structure (6) for a motor vehicle (2), comprising the steps: a. Selection of a first large cast component (10) from a modular kit containing a plurality of different large cast components (8, 10), b. Selection of at least one second large cast component (8) from the modular system, wherein the second large cast component (8) has an interface (34) for connecting to the first large cast component (6), and c. Joining the first large cast component (10) to the second large cast component (8).

2. Upper large cast component (8) for a motor vehicle (2) with at least one upper longitudinal member element (12), wherein the upper large cast component (8) is designed to be connected to at least one lower large cast component (10) for a motor vehicle (2), and wherein the at least one lower large cast component (10) has at least one lower longitudinal member element (18).

3. Lower large cast component (10) for a motor vehicle (2) with at least one lower longitudinal member element (18), wherein the lower large cast component (18) is designed to be connected to at least one upper large cast component (8) for a motor vehicle (2), wherein the at least one upper large cast component (8) has at least one upper longitudinal member element (12).

4. Lower large cast component (10) according to claim 2, wherein the lower large cast component (10) is configured to be connected to at least two further large cast components (8, 16).

5. Lower large cast component (10) according to claim 2, wherein the lower large cast component is configured to be connected to a further large cast component (20), and wherein the upper large cast component (8) is configured to also be connected to the to be connected to another large cast component (20).

6. System comprising an upper large cast component (8) according to claim 2 and a lower large cast component (10) according to one of claims 3 to 5.

7. System according to claim 6, wherein the upper large cast component (8) and the lower large cast component (10) are designed to form a positive locking connection with each other.

8. System according to claim 6 or 7, wherein the upper large cast component (8) and the lower large cast component (10) are designed to be welded or bonded together.

9. Modular construction system comprising at least one lower large cast component (10) for a frame structure (6) for a motor vehicle (2) and a plurality of alternative upper large cast components (8, 38, 40) for the frame structure (6), each of which can be connected to the lower large cast component (10).

10. Motor vehicle (2) with an upper large cast component (8) according to claim 2, with a lower large cast component (10) according to one of claims 3 to 5 or with a system according to one of claims 6 to 8.

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