The invention relates to a rear frame for a self-supporting vehicle body of a motor vehicle having a girder and having a profile part of the girder, which has multiple legs, and a vehicle body of a motor vehicle having such a rear frame.
In such rear frames, the girders are frequently manufactured from sheet-metal profiles and are known from practice. The rear frames are incorporated into a vehicle body comprising sheet-metal shells. To manufacture such girders, a plurality of plates are stamped and deep-drawn. The plates are subsequently connected to one another in a welding method, for example. The number and the concrete configuration of the plates is required in order to ensure the stability of the girder and in particular produce sufficient crash safety of the entire rear frame. In addition, attachment elements are fastened to the girders to attach auxiliary frames or spring struts. The known rear frame thus requires complex manufacturing. Unnecessary material accumulations, which result in an increased weight, arise due to the overlap of the plates required for welding.
Vehicle bodies are also known in which individual node points of the vehicle body comprise cast parts, while the frame parts connecting the nodes are implemented in sheet-metal shell construction. In addition, implementing the front crossbeam of a vehicle body as a cast part is known.
The invention is based on the problem of refining a rear frame of the type cited at the beginning so that it is particularly simple to produce and has high stability.
This problem is solved according to the invention in that the profile part is manufactured from cast metal.
The form of the girder may be selected essentially freely through this design. Furthermore, in a single component, a closed box profile or profiles deviating from a box profile may be generated with little effort. In this way, the rear frame according to the invention is producible particularly cost-effectively. Furthermore, this results in particularly high bending rigidity and torsion rigidity of the rear frame according to the invention. The particularly high rigidity results in high crash safety and driving safety of the motor vehicle having the rear frame according to the invention.
Of course, components to be connected to the profile part may be produced using nearly arbitrary methods. It contributes to further reducing manufacturing costs of the rear frame according to the invention if a cover element, which connects the legs of the profile part, is manufactured from cast metal. The cover element forms a box shape having particularly high bending rigidity together with the profile part through the connection of the legs.
For example, the cover element may be welded to the profile part. It contributes to reducing the processing steps for manufacturing the girder, however, if the cover element is integrally cast with the profile part. The profile part and/or the cover element preferably have recesses and/or cross-sectional changes for weight reduction and for targeted influence of the rigidity. Such recesses may be generated easily in the cast metal during the manufacturing in the casting method. No further method step for weight reduction is necessary according to the production method in this way.
According to another advantageous refinement of the invention, it contributes to reducing the manufacturing costs of the girder if an attachment element provided for attaching a further component to the girder is integrally manufactured with the profile part from cast metal. The integral manufacturing of the attachment element contributes to reducing the number of components to be joined of the rear frame according to the invention. During the assembly of the rear frame according to the invention, the further component can simply be moved toward the attachment element and subsequently welded or screwed thereto. The attachment element thus contributes to simplifying the assembly of the rear frame. Furthermore, the girder can be manufactured correctly for the load in a particularly simple manner by an appropriate design of a casting mold for manufacturing the attachment element integrally cast with the profile part. Further reinforcements, as in sheet-metal shell constructions, are not necessary thanks to the invention.
The rear frame according to the invention has a particularly high stability if the attachment element is implemented as an attachment flange for a crossbeam.
The construction effort for introducing operating forces of the motor vehicle into the rear frame according to the invention may be kept particularly low if the attachment element is implemented as a spring plate for supporting a spring element of a rear wheel of the motor vehicle.
According to another advantageous refinement of the invention, the attachment element contributes to increasing the rigidity of the girder if the attachment element, which is implemented as a spring plate, is made conical and extends over a subarea of the leg.
An auxiliary frame for receiving various components in the rear area of the motor vehicle may be easily installed according to another advantageous refinement of the invention if the attachment element is implemented as a bearing bush for a rear axle auxiliary frame. A substantial advantage of this design is additionally that the multiple bearing eyes are situated on a common girder. In this case, the integral manufacturing of the components of the girder with the bearing eyes results in a reduction of tolerances, because the bearing eyes are on a common component. The bearing bush can be a bearing eye, a screw bush, or another arbitrarily designed element for attaching the auxiliary frame, for example.
The attachment of the girder to a plate, in particular a side plate or a floor plate of the motor vehicle, is particularly simple according to an advantageous refinement of the invention if the cover element forms a box shape with a base of the profile part which connects the ends of the legs and if a connection flange is situated on the free ends of at least one of the legs. This connection flange may be generated in the casting method of the profile part and in this way does not require any further processing steps. The connection flange can be angled from the at least one leg or protrude linearly beyond the cover element and allows the simple welding to the plate. The plate preferably connects connection flanges situated on both legs and thus contributes to stiffening the girder.
It contributes to further increasing the stability of the rear frame according to the invention if threaded bolts for screwing the girder to a further component connect the cover element and the profile part to one another. This design is suitable in particular for attaching a rear wheel suspension arm to the girder. This rear wheel suspension arm may be screwed on easily using the threaded bolts.
The rear frame according to the invention has a particularly low weight if the cast metal is a light metal.
The girder of the rear frame according to the invention may be connected easily to adjoining components in a welding method if the cast metal is a cast steel and has a wall thickness of 1 to 5 mm.
The object of the invention is also a self-supporting vehicle body, which is manufactured in sheet-metal shell construction, of a motor vehicle having a rear frame, as previously described.
The invention permits various embodiments. To further illustrate its basic principle, several thereof are shown in the drawing and described hereafter. In the figures of the drawing
Number | Date | Country | Kind |
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102008059274.9 | Nov 2008 | DE | national |