Axle support for a vehicle axle of a motor vehicle and method for producing same

Abstract

The invention relates to an axle support for a vehicle axle of a motor vehicle, which axle support is designed as a single-piece cast component having two longitudinal elements (11, 12) which extend in the longitudinal direction of the vehicle, are designed as a hollow profile at least over a longitudinal region, and transition at a respective nodal point (13, 14) into at least one transverse element (15, 16) which extends in the transverse direction of the vehicle and is likewise designed as a hollow profile at least over a longitudinal region. The longitudinal elements (11, 12) have an at least substantially continuous inner wall (31, 32) at the respective nodal points (13, 14) to the transverse element (15, 16) so that the axle support has particularly good crash properties, said axle support being able to be produced as a cast component in a correspondingly low-weight and easy-to-produce manner.

Description

[0001] Axle carrier for a vehicle axle of a motor vehicle and method for its manufacture

[0002] The invention relates to an axle carrier for a vehicle axle of a motor vehicle according to the preamble of claim 1. Furthermore, the invention relates to a method for manufacturing such an axle carrier according to the preamble of claim 6.

[0003] Such axle carriers or similar subframes, sometimes also referred to as integral beams, are known in many embodiments. For example, there are steel constructions in which individual longitudinal and transverse elements, designed as hollow profiles such as tubes or the like, are typically joined together as separate components by welding or similar processes to form a frame. At the joints where the hollow profiles are connected, the longitudinal elements, which are usually subjected to higher loads in the longitudinal direction of a collision, run continuously, while the less stressed transverse elements are interrupted.

[0004] If, however, the axle carrier is manufactured as a one-piece cast component, as shown in Fig. 1 in a partially cutaway perspective view according to the prior art, with two longitudinal elements 1, 2 extending in the longitudinal direction of the vehicle, which are designed as hollow profiles at least over a length and transition at a respective junction 3, 4 into a front or rear transverse element 5, 6 extending in the transverse direction of the vehicle, which is also designed as a hollow profile at least over a length, then a through-opening 7 is formed at the junctions 3, 4 between the respective longitudinal element 1, 2 and the corresponding transverse element 5, 6. The reason for this is that the sand core of the axle carrier, like the axle carrier itself, is manufactured as a closed frame.This wall, interrupted by the respective through-opening 7, necessitates compensatory measures to absorb correspondingly high forces, which, for example, have a counterproductive effect on the weight and manufacturing costs of the axle carrier. Such high forces acting on the longitudinal elements occur, for example, in vehicles with a short rear end and consequently a short available crash length for the longitudinal elements of the axle carrier. While this leads to buckling in steel, which allows for a large degree of deformation, aluminum castings, depending on the heat treatment, exhibit a ductility of approximately 6% and thus low deformation capacity before fracture. This results in premature failure if the aforementioned compensatory measures are not implemented.

[0005] The object of the invention is therefore to create an axle carrier and a method of the type mentioned above, by means of which an axle carrier with improved crash properties can be created.

[0006] This problem is solved according to the invention by an axle carrier having the features of claim 1 and a method having the features of claim 7. Advantageous embodiments of the invention are the subject of the dependent claims and the description.

[0007] The axle carrier according to the invention for a vehicle axle of a motor vehicle is designed as a one-piece cast component and comprises two longitudinal elements extending in the longitudinal direction of the vehicle, which are designed as hollow profiles at least over a length and transition at each node into at least one transverse element extending in the transverse direction of the vehicle, which is also designed as a hollow profile at least over a length. Preferably, the axle carrier comprises a front and a rear transverse element into which the longitudinal elements transition at their respective front and rear nodes.

[0008] To ensure that the axle carrier, which can be manufactured as a cast component with correspondingly low weight and ease of production, exhibits particularly good crash performance, the longitudinal elements have an at least substantially continuous inner wall at the respective junctions with the respective transverse element. This continuous inner wall is created by interrupting, or forming separately from, the respective core longitudinal section (forming the associated hollow profile of the longitudinal elements) and the respective core transverse section (forming the hollow profile of the corresponding transverse element) at the junction.Instead of a previously used frame-like and continuous core part, the axle carrier according to the invention is cast using a core assembly that is multi-part, or in which the respective core transverse part forming the hollow profile of the corresponding transverse element is not directly connected to, or continuous with, the core longitudinal part forming the associated hollow profile of the longitudinal elements. The gap between the respective core transverse part and the core longitudinal parts thus creates the respective inner wall of the corresponding longitudinal element at the respective nodes to the respective transverse element in the casting mold.This inner wall ensures an essentially continuous profile cross-section of the longitudinal elements of the axle carrier, even in the area of ​​the joints between the longitudinal and transverse elements, thus resulting in a force distribution within the longitudinal elements without significant load jumps or discontinuities, and therefore in more efficient force transmission. If, for example, the axle carrier, and in particular its longitudinal elements, is subjected to a force in the longitudinal direction of the vehicle during an accident, the invention results in improved crash behavior.

[0009] In a further embodiment of the invention, it has proven advantageous if the longitudinal elements have end regions that project beyond the transverse elements in the longitudinal direction of the vehicle, at which respective bearing points for attaching the axle carrier to a vehicle body shell are arranged. This allows for a particularly favorable offset between the respective nodes and the respective bearing points of the longitudinal elements from a manufacturing perspective.

[0010] It is further advantageous if an additional transverse element is provided, which is connected to the longitudinal elements via respective through-openings. Thus, a core assembly can be used during manufacturing, in which the core longitudinal parts are connected to each other via a core transverse part, which forms the additional transverse element.

[0011] In a further embodiment of the invention, each transverse element has a rib structure via which it is connected to the respective longitudinal element. This results in a particularly favorable connection at the nodes between the less stressed transverse elements and the more heavily stressed longitudinal elements. The rib structure can thus bionically, like a tree or root system, encompass the longitudinal elements both internally and externally.

[0012] The present design of the axle carrier is particularly suitable when it is manufactured as a die-cast component. This allows the manufacturing and material advantages of a die-cast component, for example and especially one made of an aluminum alloy, to be advantageously combined with the measures according to the invention intended to increase crash load capacity.

[0013] The invention also includes a method for manufacturing an axle carrier for a vehicle axle of a motor vehicle, which is designed as a one-piece cast component with two longitudinal elements extending in the longitudinal direction of the vehicle, which are designed as hollow profiles at least over a length region and transition at a respective node point into at least one transverse element extending in the transverse direction of the vehicle, which is also designed as a hollow profile at least over a length region, comprising the steps:

[0014] - Placing a core device into a mold, and

[0015] - Casting of the axle carrier, wherein, as core equipment, the respective core longitudinal part forming the associated hollow profile of the longitudinal elements and at least one core transverse part forming the hollow profile of the at least one transverse element are placed in the casting mold, wherein the core transverse part is interrupted in the area of ​​the respective node or is formed separately from the core longitudinal parts.

[0016] This method thus makes it possible to create an axle carrier in which the longitudinal elements have at least a substantially continuous inner wall at the respective nodes to the respective transverse element - with the advantages described above.

[0017] In particular, the core assembly comprises, in addition to the two longitudinal core sections, a front transverse core section forming a front transverse element and a rear transverse core section forming a rear transverse element, which are placed in the casting mold, the two transverse core sections being formed separately from the longitudinal core sections. This results in the desired frame-like shape of the axle carrier.

[0018] Furthermore, it has proven advantageous to place a core cross-element, forming another transverse element, into the mold together with the core longitudinal elements that are integrally connected to it. This allows for the creation of an easily handled main part of the core assembly, which also simplifies the casting process.

[0019] Further features of the invention will become apparent from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown in the figures alone, are not only usable in the combinations specified, but also in other combinations or on their own.

[0020] The invention will now be explained in more detail with reference to a preferred embodiment and the drawings. The drawings show:

[0021] Fig. 1 shows a perspective view of an axle carrier designed as a one-piece cast component according to the prior art,

[0022] Fig. 2 shows a perspective view of an axle carrier designed as a one-piece cast component according to the invention,

[0023] Fig. 3 shows a top view of the axle carrier according to Fig. 2.

[0024] Fig. 4 shows a perspective view of the axle carrier, partially cut away in the rear area, according to Figs. 2 and 3.

[0025] Fig. 5 shows a perspective view of the axle carrier, which is partially cut away in the rear area, analogous to Fig. 4.

[0026] Fig. 6 shows a perspective view of the axle carrier, partially cut away in the front area, according to Figs. 2 and 3.

[0027] Figs. 7a, 7b are respective partial and cut perspective views of one of the two longitudinal elements of the axle carrier in the area of ​​its rear end, as well as

[0028] Fig. 8 shows a perspective view of a core arrangement for insertion into a

[0029] Mold for casting the axle carrier according to Figs. 2 to 7b. While Fig. 1 shows an axle carrier according to the prior art, the axle carrier according to the invention and the associated method for its manufacture will be explained below with reference to Figs. 2 to 8.

[0030] According to Figures 2 and 3, which show the axle carrier for a vehicle axle of a motor vehicle in a perspective view and a top view, it is designed as a one-piece cast component, in particular an aluminum die-cast component, and comprises two longitudinal elements 11, 12 extending in the longitudinal direction of the vehicle when installed. These longitudinal elements are integrally connected at respective nodes 13, 14 to a front and rear transverse element 15, 16 extending in the transverse direction of the vehicle, forming a frame-like structure. In the embodiment shown here, the longitudinal elements 11, 12 are also integrally connected to each other via a further, central transverse element 17. In the simplest embodiment, however, it would suffice if the two longitudinal elements 11, 12 were connected to each other via only one transverse element 15, 16.

[0031] Both the longitudinal elements 11, 12 and the transverse elements 15, 16, 17 are, in this case, designed as hollow profiles at least over a length, and here even at least almost completely. The hollow profiles are produced by creating a core assembly 18, visible in a perspective view in Fig. 8, which comprises respective longitudinal core sections 19, 20 and respective transverse core sections 21, 22, 23, and which is placed as a whole into a casting mold, in a manner described in more detail below.

[0032] As can be further seen from Figs. 2 and 3, bearing eyes or bearing points 24 are arranged at the rear end of the axle carrier near the respective nodes 13 between the longitudinal elements 11, 12 and the rear transverse element 15, via which the axle carrier, which in this case is designed as a rear axle carrier, can be mounted on the vehicle body shell, for example by means of respective buffer elements.

[0033] At their front ends, the longitudinal elements 11, 12 each have end sections 25 that project forward in the longitudinal direction of the vehicle relative to the front transverse element 16. At these end sections, respective bearing points 26 are arranged for attaching the axle carrier to the vehicle body, for example, by means of respective buffer elements. As can be seen in Fig. 8, the front and rear core cross sections 21, 22 are interrupted or formed separately from the core longitudinal sections 19, 20 in the area of ​​their respective nodes 13, 14. The two core longitudinal sections 19, 20 are connected to each other only via the central core cross section 23 directly in the area of ​​the nodes 27. The rear core cross section 22 is connected to the central core cross section via respective webs 28, so that the core longitudinal sections 19, 20, the central core cross section 23, and the rear core cross section 22 form a main core part of the core assembly 18.The front core cross-section 21, however, is completely separate from the main core section. The entire core assembly 18 is thus designed in two parts, although other configurations are obviously conceivable. For example, the rear core cross-section 22 could be designed separately from the core longitudinal sections 19, 20. The middle core cross-section 23 could also be designed separately from the core longitudinal sections 19, 20 or even be absent altogether. In general, the simplest embodiment would be a core assembly 18 with only two core longitudinal elements 19, 20 and a core cross-section 21, 22, 23 interrupted in the area of ​​the account positions 13, 14, 27.

[0034] Due to the interruption of the formation of the rear core cross-section 22 in the area of ​​the nodes 13 by the longitudinal core sections 19, 20, or due to the completely separate and thus also interrupted formation of the front core cross-section 21 from the longitudinal core sections 19, 20, in the area of ​​these interruptions 29, 30, after the core assembly 18 has been placed in the mold and after casting, in particular die casting, at the respective nodes 13, 14 between the longitudinal elements 19 20 to the front or rear transverse element 15, 16, a respective, at least substantially continuous inner wall 31, 32 of the respective hollow profile of the then cast longitudinal elements 11, 12 of the axle carrier is formed.

[0035] This respective inner wall 32 in the area of ​​the rear joint 14 is particularly recognizable in conjunction with Figures 4 and 5, which each show sectional perspective views in the area of ​​the joint 14 between the rear transverse element 15 and the longitudinal elements 11, 12. The respective inner wall 31 in the area of ​​the front joints 13 between the front transverse element 16 and the longitudinal elements 11, 12 is particularly shown in a sectional perspective view in Figure 6. The respective inner wall 31, 32 extends in the longitudinal direction of the vehicle and closes off the respective transverse element 15, 16 or the hollow cross-section of the respective longitudinal element 11, 12.The respective inner wall 31, 32 thus ensures an at least substantially continuous profile cross-section of the longitudinal elements 11, 12 of the axle carrier, even in the area of ​​the nodes 13, 14 between the longitudinal elements 11, 12 and the transverse elements 21, 22, and thus results in a force distribution within the longitudinal elements 11, 12 without significant load jumps or discontinuities, and therefore in more efficient force transmission. If, for example, the axle carrier, and in particular its longitudinal elements 11, 12, are subjected to a force in the longitudinal direction of the vehicle due to an accident, the invention results in improved crash behavior.

[0036] Since the further, middle core cross-section 23 is directly and immediately connected to the longitudinal core sections 19, 20, the middle cross-section 17, on the other hand, has respective through-openings 33 at the nodes 27 with the longitudinal elements 11, 12.

[0037] Figures 7a and 7b show partial and sectioned perspective views of one of the two longitudinal elements 11, 12 of the axle carrier in the region of its rear end. Here, too, the respective inner wall 32 is visible in the region of the rear joint 14 between the rear transverse element 15 and the corresponding longitudinal element 11, 12. Furthermore, it is evident that the respective transverse element 15 has a rib structure 34 with respective inner ribs 35, via which the transverse element 15 is connected to the respective longitudinal element 11, 12 – for example, by means of the respective inner wall 32. The rib structure 34 can thus bionically, in the manner of a tree or root system, encompass the longitudinal elements 11, 12 both internally and externally.

[0038] Reference symbol list

[0039] longitudinal element

[0040] Longitudinal element, rear node, front node, rear transverse element, front transverse element, middle transverse element, core assembly, core longitudinal part

[0041] Core longitudinal section, front core transverse section, rear core transverse section, middle core transverse section, front bearing point

[0042] End area rear bearing point middle node

[0043] footbridges

[0044] Interruption of interior wall

[0045] Interior wall

[0046] Through-opening rib structure

[0047] Ribs

Claims

Patent claims 1. Axle carrier for a vehicle axle of a motor vehicle, which is designed as a one-piece cast component with two longitudinal elements (11, 12) extending in the longitudinal direction of the vehicle, which are designed as hollow profiles at least over a length region and transition at a respective node (13, 14) into at least one transverse element (15, 16) extending in the transverse direction of the vehicle, which is also designed as a hollow profile at least over a length region, characterized in that the longitudinal elements (11, 12) have an at least substantially continuous inner wall (31, 32) at the respective nodes (13, 14) to the transverse element (15, 16).

2. Axle carrier according to claim 1, characterized in that the longitudinal elements (11, 12) transition at respective front and rear node points (13, 14) into a front and rear transverse element (15, 16) respectively, extending in the transverse direction of the vehicle.

3. Axle carrier according to claim 1 or 2, characterized in that the longitudinal elements (11, 12) have respective end areas (25) projecting in the longitudinal direction of the vehicle relative to the transverse elements (15, 16), at which respective bearing points (24, 26) are arranged for fastening the axle carrier to a motor vehicle body shell.

4. Axle carrier according to one of the preceding claims, characterized in that a further transverse element (17) is provided which is connected to the longitudinal elements (11, 12) via respective through-openings (33).

5. Axle carrier according to one of the preceding claims, characterized in that the respective transverse element (15, 16) has a rib structure (34) via which the transverse element (15, 16) is connected to the respective longitudinal element (11, 12).

6. Axle carrier according to one of the preceding claims, characterized in that the axle carrier is designed as a die-cast component.

7. Method for manufacturing an axle carrier for a vehicle axle of a motor vehicle, which is designed as a one-piece cast component with two longitudinal elements (11, 12) extending in the longitudinal direction of the vehicle, which are designed as hollow profiles at least over a length region and transition at a respective node (13, 14) into at least one transverse element (15, 16) extending in the transverse direction of the vehicle, which is also designed as a hollow profile at least over a length region, comprising the steps: - Placing a core device (18) into a casting mold, and - Casting of the axle carrier, characterized in that as core device (18) respective core longitudinal part (19, 20) forming the associated hollow profile of the longitudinal elements (11, 12) and at least one core transverse part (21, 22) forming the hollow profile of the at least one transverse element (15, 16, 17) are placed in the casting mold, wherein the core transverse part (21, 22) is formed in the area of ​​the node (13, 14) interrupted by the core longitudinal parts (19, 20).

8. Method according to claim 7, characterized in that a front core cross-section (21) forming a front transverse element (15) and a rear core cross-section (22) forming a rear transverse element (16) are placed in the casting mold, wherein the two core cross-sections (21 , 22) are formed separately from the core longitudinal sections (19, 20).

9. Method according to claim 7 or 8, characterized in that a core transverse part (23) forming a further transverse element (15, 16, 17) together with the core longitudinal parts (19, 20) which are connected in one part to it is placed in the casting mold.

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